High density electrode mapping catheter

ABSTRACT

An integrated electrode structure can comprise a catheter shaft comprising a proximal end and a distal end, the catheter shaft defining a catheter shaft longitudinal axis. A flexible tip portion can be located adjacent to the distal end of the catheter shaft, the flexible tip portion comprising a flexible framework. A plurality of microelectrodes can be disposed on the flexible framework and can form a flexible array of microelectrodes adapted to conform to tissue. A plurality of conductive traces can be disposed on the flexible framework, each of the plurality of conductive traces can be electrically coupled with a respective one of the plurality of microelectrodes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 15/331,562 (the '562 application), filed 21 Oct. 2016, now pending.This application claims priority to U.S. application No. 62/244,565 (the'565 application), filed 21 Oct. 2015. This application claims priorityto U.S. application No. 62/324,067 (the '067 application), filed 18 Apr.2016. The '562 application, the '565 application, and the '067application are hereby incorporated by reference as though fully setforth herein. This application is related to U.S. application Ser. No.16/781,499 (the '499 application) titled “HIGH DENSITY ELECTRODE MAPPINGCATHETER,” filed 4 Feb. 2020, now pending. This application is relatedto U.S. application Ser. No. 15/331,369 (the '369 application) titled“HIGH DENSITY ELECTRODE MAPPING CATHETER,” filed 21 Oct. 2016, nowissued under U.S. Pat. No. 10,362,954 on 30 Jul. 2019. Both the '499application and the '369 application are hereby incorporated byreference as though fully set forth herein.

A. FIELD OF THE DISCLOSURE

This disclosure relates to a high density electrode mapping catheter.

B. BACKGROUND ART

Catheters have been used for cardiac medical procedures for many years.Catheters can be used, for example, to diagnose and treat cardiacarrhythmias, while positioned at a specific location within a body thatis otherwise inaccessible without a more invasive procedure.

Conventional mapping catheters may include, for example, a plurality ofadjacent ring electrodes encircling the longitudinal axis of thecatheter and constructed from platinum or some other metal. These ringelectrodes are relatively rigid. Similarly, conventional ablationcatheters may comprise a relatively rigid tip electrode for deliveringtherapy (e.g., delivering RF ablation energy) and may also include aplurality of adjacent ring electrodes. It can be difficult to maintaingood electrical contact with cardiac tissue when using theseconventional catheters and their relatively rigid (or nonconforming),metallic electrodes, especially when sharp gradients and undulations arepresent.

Whether mapping or forming lesions in a heart, the beating of the heart,especially if erratic or irregular, complicates matters, making itdifficult to keep adequate contact between electrodes and tissue for asufficient length of time. These problems are exacerbated on contouredor trabeculated surfaces. If the contact between the electrodes and thetissue cannot be sufficiently maintained, quality lesions or accuratemapping are unlikely to result.

The foregoing discussion is intended only to illustrate the presentfield and should not be taken as a disavowal of claim scope.

BRIEF SUMMARY

Various embodiments herein provide an integrated electrode structure. Inat least one embodiment, the integrated electrode structure can comprisea catheter shaft comprising a proximal end and a distal end, thecatheter shaft defining a catheter shaft longitudinal axis. A flexibletip portion can be located adjacent to the distal end of the cathetershaft, the flexible tip portion comprising a flexible framework. Aplurality of microelectrodes can be disposed on the flexible frameworkand can form a flexible array of microelectrodes adapted to conform totissue. A plurality of conductive traces can be disposed on the flexibleframework, each of the plurality of conductive traces can beelectrically coupled with a respective one of the plurality ofmicroelectrodes.

Various embodiments herein provide an integrated electrode structurethat comprises a catheter shaft that includes a proximal end and adistal end, the catheter shaft defining a catheter shaft longitudinalaxis. A flexible tip portion can be located adjacent to the distal endof the catheter shaft, the flexible tip portion comprising a flexibleframework that includes an inner understructure and an outerunderstructure. A plurality of microelectrodes can be disposed on a topsurface of the inner understructure and outer understructure and abottom surface of the inner understructure and outer understructure,forming a flexible array of microelectrodes adapted to conform totissue. A plurality of conductive traces can be disposed on the topsurface of the inner understructure and outer understructure and abottom surface of the inner understructure and outer understructure,each of the plurality of conductive traces being electrically coupledwith a respective one of the plurality of microelectrodes.

Various embodiments herein provide a method for determining a degree ofcontact between a first electrode and tissue. In some embodiments, themethod can include receiving a first electrical signal from the firstelectrode disposed on a first side of a tip portion of a medical device.In some embodiments, the method can include receiving a secondelectrical signal from a second electrode disposed on a second side ofthe tip portion of the medical device, wherein the first electrode andthe second electrode are disposed vertically adjacent with respect toone another. In some embodiments, the method can include determining thedegree of contact between the first electrode and the tissue based on acomparison between the first electrical signal and the second electricalsignal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a top view of a high density electrode mapping catheter,according to various embodiments of the present disclosure.

FIG. 1B depicts an isometric side and top view of the high densityelectrode mapping catheter in FIG. 1A, according to various embodimentsof the present disclosure.

FIG. 2A depicts an isometric side and top view of an inboardunderstructure of a high density electrode mapping catheter in FIG. 1A,according to various embodiments of the present disclosure.

FIG. 2B depicts an isometric side and top view of a coated inboardunderstructure of a high density electrode mapping catheter, accordingto various embodiments of the present disclosure.

FIGS. 3A to 3K depict a top view and end view of a second inboard arm ofthe high density electrode mapping catheter and associated processingsteps, according to various embodiments of the present disclosure.

FIG. 4A depicts a top view of a processed inboard understructure,according to various embodiments of the present disclosure.

FIG. 4B depicts an enlarged portion (indicated by dotted oval 4B) of afirst inboard arm of the processed inboard understructure depicted inFIG. 4A, according to various embodiments of the present disclosure.

FIG. 4C depicts a cross-sectional view of the first outboard arm alongthe line cc, in FIG. 4B, according to various embodiments of the presentdisclosure.

FIG. 4D depicts a cross-sectional view of the first outboard arm alongline dd, in FIG. 4B, according to various embodiments of the presentdisclosure.

FIG. 5 depicts a cross-sectional view of patterned conductive tracesformed on a top and bottom of a conductive flexible framework, accordingto various embodiments of the present disclosure.

FIG. 6A depicts the conductive flexible framework after an additionallayer of dielectric material has been stripped from a distal portion ofeach of the electrically conductive traces, leaving an exposed area,according to various embodiments of the present disclosure.

FIG. 6B depicts a processed conductive flexible framework after theadditional layer of dielectric material has been stripped from a distalportion of each of the electrically conductive traces, leaving anexposed area on which solder has been deposited, according to variousembodiments of the present disclosure.

FIG. 6C depicts a cross-sectional end view of the processed conductiveflexible framework depicted in FIG. 6B along the line ee, according tovarious embodiments of the present disclosure.

FIG. 6D depicts a hollow cylindrical band, according to variousembodiments of the present disclosure.

FIG. 6E depicts a hollow cylindrical band in which solder is deposited,according to various embodiments of the present disclosure.

FIG. 6F depicts an isometric side and front view of the hollowcylindrical band depicted in FIG. 6D, according to various embodimentsof the present disclosure.

FIG. 6G depicts a hollow cylindrical band coaxially aligned with theprocessed conductive flexible framework, according to variousembodiments of the present disclosure.

FIG. 6H depicts a processing step associated with the hollow cylindricalband, according to various embodiments of the present disclosure.

FIG. 6I depicts a swaged hollow cylindrical band after performing theprocessing step described in relation to FIG. 6H, according to variousembodiments of the present disclosure.

FIG. 6J depicts the swaged hollow cylindrical band and the processedconductive flexible framework after a solder reflow process, accordingto various embodiments of the present disclosure.

FIGS. 7A-7C depict a top view and end view of a second inboard arm ofthe high density electrode mapping catheter, wherein a flexibleframework of the high density electrode mapping catheter is formed froma flexible substrate and associated processing steps, according tovarious embodiments of the present disclosure.

FIG. 8A depicts a top view of a processed inboard understructure,according to various embodiments of the present disclosure.

FIG. 8B depicts an enlarged portion (indicated by dotted oval 8B) of afirst inboard arm of the processed inboard understructure depicted inFIG. 8A, according to various embodiments of the present disclosure.

FIG. 8C depicts an enlarged portion (indicated by dotted oval 8C) of afirst inboard arm of the processed inboard understructure depicted inFIG. 8A, according to various embodiments of the present disclosure.

FIG. 9A depicts a top view of a bottom mold for an overmolding process,according to various embodiments of the present disclosure.

FIG. 9B depicts a processed inboard understructure inserted into thebottom mold depicted in FIG. 9A, according to various embodiments of thepresent disclosure.

FIG. 9C depicts a cross-sectional side view of an assembled mold and theprocessed inboard understructure in FIG. 9B along line hh in FIG. 9B,according to various embodiments of the present disclosure.

FIG. 9D depicts a top view of bottom mold and an overmolded inboardunderstructure after an overmolding process has been performed,according to various embodiments of the present disclosure.

FIG. 9E depicts a cross-sectional side view of an assembled mold and theovermolded inboard understructure in FIG. 9D along line ii in FIG. 9D,according to various embodiments of the present disclosure.

FIG. 10A depicts a cross-sectional side view of an ablation fixture inwhich the overmolded inboard understructure has been placed, accordingto various embodiments of the present disclosure.

FIG. 10B depicts a top view of the ablation fixture in FIG. 10A after anablation processing step has been completed and an ablated overmoldedinboard understructure, according to various embodiments of the presentdisclosure.

FIG. 10C depicts a top view of the ablated overmolded inboardunderstructure after being ejected from the ablation fixture depicted inFIG. 10B, according to various embodiments of the present disclosure.

FIG. 11 depicts mechanical properties of various materials that can beused for forming understructures of the flexible tip portion, accordingto various embodiments of the present disclosure.

FIG. 12A depicts a top view of a proximal end of an inboardunderstructure, according to various embodiments of the presentdisclosure.

FIG. 12B depicts a top view of an enlarged portion (indicated by dottedcircle 12B) of the frame locks depicted on a proximal end of the inboardunderstructure depicted in FIG. 12A, according to various embodiments ofthe present disclosure.

FIG. 12C depicts a top view of an enlarged portion (indicated by dottedcircle 12C) of electrical connections depicted in FIG. 12B, according tovarious embodiments of the present disclosure.

FIG. 12D is a cross-sectional view of FIG. 12C along line mm, accordingto various embodiments of the present disclosure.

FIG. 12E depicts a top view of wires electrically coupled via anelectrical connection, according to various embodiments of the presentdisclosure.

FIG. 13A depicts a top view of a plurality of electrical connectionsdisposed on a first inboard arm; second inboard arm, first outboard arm;and second outboard arm of a flexible framework of a flexible tipportion of the high density electrode mapping catheter, according tovarious embodiments of the present disclosure.

FIG. 13B depicts a top view of a subset of the electrical connectionsdisposed on an first inboard arm; second inboard arm, first outboardarm; and second outboard arm of a flexible framework of a flexible tipportion of the high density electrode mapping catheter depicted in FIG.13A, according to various embodiments of the present disclosure.

FIG. 14 depicts a method flow diagram for a process for forming anintegrated electrode structure that includes a conductiveunderstructure, according to various embodiments of the presentdisclosure.

FIG. 15 depicts a method flow diagram for a process for forming anintegrated electrode structure that includes a substrate understructure,according to various embodiments of the present disclosure.

FIG. 16 depicts a side view of an arm of the high density electrodemapping catheter, according to various embodiments of the presentdisclosure.

FIGS. 17A to 17F depict a side view of an arm of the high densityelectrode mapping catheter and associated processing steps, according tovarious embodiments of the present disclosure.

FIGS. 18A to 18G depict top views of embodiments of understructure of ahigh density electrode mapping catheter in FIG. 1A, according to variousembodiments of the present disclosure.

FIG. 19A depicts a top view of a flexible tip portion of a high densityelectrode mapping catheter that includes a plurality of electrodes,according to various embodiments of the present disclosure.

FIG. 19B depicts an enlarged top view of a pair of contact pads disposedon the flexible tip portion depicted in FIG. 19A, according to variousembodiments of the present disclosure.

FIG. 19C depicts an enlarged top view of a microelectrode disposed onthe flexible tip portion depicted in FIG. 19A, according to variousembodiments of the present disclosure.

FIG. 19D depicts a schematic side view of microelectrodes disposed on atop and bottom of the flexible tip portion depicted in FIG. 19A,according to various embodiments of the present disclosure.

FIG. 20 depicts an isometric side, top, and distal end view of theflexible tip portion depicted in FIG. 19A, according to variousembodiments of the present disclosure.

FIG. 21 depicts a top view of an understructure of a flexible tipportion of a high density electrode mapping catheter, according tovarious embodiments of the present disclosure.

FIG. 22 depicts a top view of an alternate embodiment of anunderstructure of a high density electrode mapping catheter, accordingto various embodiments of the present disclosure.

FIGS. 23A-23F depict an isometric top and side view of an arm of anunderstructure of a high density electrode mapping catheter, accordingto various embodiments of the present disclosure.

FIG. 24A depicts a top view of an understructure of a flexible tipportion 660 of a high density electrode mapping catheter that includes aplurality of electrodes, traces, and a contact pad, according to variousembodiments of the present disclosure.

FIG. 24B depicts an enlarged top view of a portion of a second outboardarm of the flexible tip portion depicted in FIG. 24A, according tovarious embodiments of the present disclosure.

FIG. 24C depicts an enlarged top view of a portion of the flexible tipportion that includes a contact pad depicted in FIG. 24A, according tovarious embodiments of the present disclosure.

FIG. 25A depicts a top view of an understructure of a flexible tipportion of a high density electrode mapping catheter that includes aplurality of electrodes and rows of contact pads, according to variousembodiments of the present disclosure.

FIG. 25B depicts an enlarged view of the flexible tip portion depictedin FIG. 25A, according to various embodiments of the present disclosure.

FIG. 25C depicts an enlarged top view of the mounting portion of theflexible tip portion depicted in FIG. 25A, according to variousembodiments of the present disclosure.

FIG. 26 depicts a flexible tip portion of a high density electrodemapping catheter similar to that depicted in FIG. 19A that includes aplurality of wires connected to contact pads disposed on a mountingportion, according to various embodiments of the present disclosure.

FIG. 27A depicts sections of flex cable, according to variousembodiments of the present disclosure.

FIG. 27B depicts a cross-sectional end view of a ground trace of theflex cable depicted in FIG. 27A, according to various embodiments of thepresent disclosure.

FIG. 28 depicts a flexible tip portion of a high density electrodemapping catheter disposed in a distal end of a catheter shaft, accordingto various embodiments of the present disclosure.

FIG. 29 depicts a high density electrode mapping catheter, according tovarious embodiments of the present disclosure.

FIG. 30 depicts another embodiment of a high density electrode mappingcatheter, according to various embodiments of the present disclosure.

FIG. 31 depicts a schematic and block diagram view of an electromagneticnavigation system, according to various embodiments of the presentdisclosure.

FIG. 32 depicts a method control block flow diagram for determining adegree of contact between a first electrode and tissue, according tovarious embodiments of the present disclosure.

FIG. 33 depicts a method control block flow diagram for determining acardiac activation associated with endocardial tissue, according tovarious embodiments of the present disclosure.

DETAILED DESCRIPTION

The contents of International Application No. PCT/US2014/011940 entitledFlexible High-Density Mapping Catheter Tips and Flexible AblationCatheter Tips with Onboard High-Density Mapping Electrodes is herebyincorporated by reference.

FIG. 1A depicts a top view of a high density electrode mapping catheter101 and FIG. 1B is an isometric side and top view of the high densityelectrode mapping catheter 101, according to various embodiments of thepresent disclosure. In some embodiments, the high density electrodemapping catheter 101 can include a flexible tip portion 110 that forms aflexible array of microelectrodes 102. This planar array (or ‘paddle’configuration) of microelectrodes 102 comprises four side-by-side,longitudinally-extending arms 103, 104, 105, 106, which can form aflexible framework on which the microelectrodes 102 are disposed. Thefour microelectrode-carrier arms comprise a first outboard arm 103, asecond outboard arm 106, a first inboard arm 104, and a second inboardarm 105. These arms can be laterally separated from each other.

Each of the four arms can carry a plurality of microelectrodes 102. Forexample, each of the four arms can carry microelectrodes 102 spacedalong a length of each of the four arms. Although each of the highdensity electrode mapping catheters 101 depicted in FIGS. 1A and 1Bdepict four arms, the high density electrode mapping catheters 101 couldcomprise more or fewer arms. Additionally, while the high densityelectrode mapping catheter 101 depicted in FIGS. 1A and 1B depict 18electrodes (e.g., 5 microelectrodes on first outboard arm 103 and secondoutboard arm 106 and 4 microelectrodes on first inboard arm 104 andsecond inboard arm 105), the catheters can include more or fewer than 18electrodes. In addition, the first outboard arm 103 and second outboardarm 106 can include more or fewer than 5 microelectrodes and the firstinboard arm 104 and second inboard arm 105 can include more or fewerthan 4 microelectrodes).

In some embodiments, the microelectrodes 102 can be used in diagnostic,therapeutic, and/or mapping procedures. For example and withoutlimitation, the microelectrodes 102 can be used for electrophysiologicalstudies, pacing, cardiac mapping, and ablation. In some embodiments, themicroelectrodes 102 can be used to perform unipolar or bipolar ablation.This unipolar or bipolar ablation can create specific lines or patternsof lesions. In some embodiments, the microelectrodes 102 can receiveelectrical signals from the heart, which can be used forelectrophysiological studies. In some embodiments, the microelectrodes102 can perform a location or position sensing function related tocardiac mapping.

In some embodiments, the high density electrode mapping catheter 101 caninclude a catheter shaft 107. The catheter shaft 107 can include aproximal end and a distal end. The distal end can include a connector108, which can couple the distal end of the catheter shaft 107 to aproximal end of the planar array. The catheter shaft 107 can define acatheter shaft longitudinal axis aa, as depicted in FIG. 1A, along whichthe first outboard arm 103, first inboard arm 104, second inboard arm105, and second outboard arm 106 can generally extend parallel inrelation therewith. The catheter shaft 107 can be made of a flexiblematerial, such that it can be threaded through a tortuous vasculature ofa patient. In some embodiments, the catheter shaft 107 can include oneor more ring electrodes 111 disposed along a length of the cathetershaft 107. The ring electrodes 111 can be used for diagnostic,therapeutic, and/or mapping procedures, in an example.

As depicted in FIG. 1B, the flexible tip portion 110 can be adapted toconform to tissue (e.g., cardiac tissue). For example, when the flexibletip portion 110 contacts tissue, the flexible tip portion can deflect,allowing the flexible framework to conform to the tissue. In someembodiments, the arms (or the understructure of the arms) comprising thepaddle structure (or multi-arm, electrode-carrying, flexible framework)at the distal end of the catheters depicted in FIGS. 1A and 1B arepreferably constructed from a flexible or spring-like material such asNitinol and/or a flexible substrate, as discussed herein. Theconstruction (including, for example, the length and/or diameter of thearms) and material of the arms can be adjusted or tailored to becreated, for example, desired resiliency, flexibility, foldability,conformability, and stiffness characteristics, including one or morecharacteristics that may vary from the proximal end of a single arm tothe distal end of that arm, or between or among the plurality of armscomprising a single paddle structure. The foldability of materials suchas Nitinol and/or flexible substrate provide the additional advantage offacilitating insertion of the paddle structure into a delivery catheteror introducer, whether during delivery of the catheter into the body orremoval of the catheter from the body at the end of a procedure.

Among other things, the disclosed catheters, with their plurality ofmicroelectrodes, are useful to (1) define regional propagation maps ofparticularly sized areas (e.g., one centimeter square areas) within theatrial walls of the heart; (2) identify complex fractionated atrialelectrograms for ablation; (3) identify localized, focal potentialsbetween the microelectrodes for higher electrogram resolution; and/or(4) more precisely target areas for ablation. These mapping cathetersand ablation catheters are constructed to conform to, and remain incontact with, cardiac tissue despite potentially erratic cardiac motion.Such enhanced stability of the catheter on a heart wall during cardiacmotion provides more accurate mapping and ablation due to sustainedtissue-electrode contact. Additionally, the catheters described hereinmay be useful for epicardial and/or endocardial use. For example, theplanar array embodiments depicted herein may be used in an epicardialprocedure where the planar array of microelectrodes is positionedbetween the myocardial surface and the pericardium. Alternatively theplanar array embodiments may be used in an endocardial procedure toquickly sweep and/or analyze the inner surfaces of the myocardium andquickly create high-density maps of the heart tissue's electricalproperties.

FIG. 2A is an isometric side and top view of an inboard understructure120 (also referred to herein as inner understructure) of a high densityelectrode mapping catheter in FIG. 1A, according to various embodimentsof the present disclosure. In some embodiments, the inboardunderstructure 120 can be formed from a flexible or spring-like materialsuch as Nitinol and/or a flexible substrate, as discussed herein. Theinboard understructure 120 can include a first inboard armunderstructure 121 and a second inboard arm understructure 122. Althoughnot shown, the outboard understructure (also referred to herein as outerunderstructure) that provides the understructure for the first outboardarm 103 and the second outboard arm 106 can be formed and/or processedin a manner analogous to that discussed in relation to the inboardunderstructure 120. Further, if the high density electrode mappingcatheter includes additional arms, those arms can be formed and/orprocessed in a manner analogous to that discussed in relation to theinboard understructure 120. For the sake of brevity, discussion isdirected towards the inboard understructure 120. As depicted, theinboard understructure 120 can include a first inboard mounting arm 123and a second inboard mounting arm 124. The inboard mounting arms can beinserted into a distal end of the catheter 107 and through the connector108 and can be used to connect the flexible tip portion 110 to thedistal end of the catheter 107. In some embodiments, the inboardmounting arms can be inserted through a torsional spacer, as discussedherein.

As depicted in FIG. 2A, the inboard understructure 120 (and although notdepicted, the outboard understructure) can be formed from a planar pieceof material. However, in some embodiments, the inboard understructure120 (and the outboard understructure) can be formed from a cylindrical,square, or other shape of understructure. In some embodiments, theinboard understructure 120 and the outboard understructure can be formedfrom a single unitary piece of material, as discussed in relation toFIGS. 18A to 18G.

FIG. 2B depicts an isometric side and top view of a coated inboardunderstructure 122-1 of a high density electrode mapping catheter 101,according to various embodiments of the present disclosure. In somecurrent practices, high density electrode mapping catheters can beassembled using tubular subassemblies for the inboard understructure andthe outboard understructure. One reason for the use of tubing whenassembling the understructures is to allow wire to be threaded throughthe tubing for connection of each individual microelectrode. Thisprocess can be labor and/or cost intensive, since each wire may beindividually threaded through the tubing and individually connected witheach microelectrode. Further, ensuring that a reliable electricalconnection is established between each microelectrode and its wire canbe challenging.

In addition, use of tubing can result in a less predictable deflectionof the flexible tip portion since the walls of the tubing may besymmetrical and are not biased to bend in a particular manner.Embodiments of the present disclosure can provide for a less labor andcost intensive assembly process, as well as provide for a morepredictable deflection of the flexible tip portion 110. In someembodiments, a plurality of patterned conductive traces can be disposedon a flexible framework of an expandable structure. For instance, theplurality of patterned conductive traces can be disposed on a flexibleframework of an expandable medical device structure. Some embodiments ofthe present disclosure can provide for a flexible tip portion 110 thatincludes a plurality of patterned conductive traces disposed on theflexible framework of the flexible tip portion 110, as discussed herein,in lieu of individually run wires. The patterned conductive traces canbe electrically coupled with the plurality of microelectrodes 102disposed on the flexible tip portion 110. The patterned conductivetraces can be formed via a process that is less labor and/or costintensive than current practices. Some embodiments of the presentdisclosure can provide a means for testing an electrical connectionbetween the microelectrodes 102 and the patterned conductive tracesand/or wires, which electrically connect the plurality ofmicroelectrodes 102.

In some embodiments of the present disclosure, the inboardunderstructure can be coated with a dielectric material. In someembodiments, examples of the dielectric material can include parylene.Other dielectric materials such as a polyimide (e.g., PI-2771 or HD-4004available from HD Microsystems) and/or an epoxy (e.g., SU8 epoxyavailable from MicroChem Corp), etc. can be used in accordance withdesign and end-use requirements. In some embodiments where theunderstructure is an electrically conductive material, the dielectriccan electrically insulate the conductive traces, as discussed herein,from the electrically conductive material.

FIGS. 3A to 3K depict a top view and end view of a second inboard arm ofthe high density electrode mapping catheter and associated processingsteps, according to various embodiments of the present disclosure (thetop view is depicted above the end view in FIGS. 3A to 3K). FIG. 3Adepicts a conductive flexible framework 130 of the inboardunderstructure 120 coated with a dielectric material 131, according tovarious embodiments of the present disclosure. In an example, thedielectric material can be applied to the conductive flexible framework130 to coat the conductive flexible framework 130 in the dielectricmaterial 131 to provide an electrically insulative layer, upon whichpatterned conductive traces can be disposed.

FIG. 3B depicts the conductive flexible framework 130 of the inboardunderstructure 120 (also referred to as flexible framework) coated withthe dielectric material 131 and a mask 134 (also referred to as maskedportion), according to various embodiments of the present disclosure. Inan example, one or more unmasked trace pattern portions 132-1, 132-2,132-3 can be formed on the dielectric coating of the conductive flexibleframework 130 via the mask 134. In some embodiments, the mask 134 canform channels 136 along the dielectric material, in which a conductivematerial can be deposited to form the electrically conductive traces.

FIG. 3C depicts seed layers 138-1, 138-2, 138-3 deposited in theunmasked trace pattern portions 132-1, 132-2, 132-3 of FIG. 3B,according to various embodiments of the present disclosure. In someembodiments, the seed layers can be deposited within the channels 136 topartially fill the channels with the seed layers 138-1, 138-2, 138-3. Insome embodiments, the seed layers 138-1, 138-2, 138-3 can include copper(Cu), nickel (Ni), aluminum (Al), etc. The seed layers 138-1, 138-2,138-3 can provide a base layer upon which a layer of conductive materialcan be deposited. In an example, the seed layers 138-1, 138-2, 138-3 canprovide an interface between the dielectric material 131 and aconductive material which is deposited on the conductive flexibleframework 130 to form electrically conductive traces. For instance, theseed layer can allow for the conductive material to be adhered to thedielectric material 131 (e.g., the conductive material is adhered to thedielectric material 131 via the seed layers 138-1, 138-2, 138-3).

FIG. 3D depicts the seed layers 138-1, 138-2, 138-3 being plated with aconductive material (e.g., copper) to form electrically conductivetraces 140-1, 140-2, 140-3, according to various embodiments of thepresent disclosure. In an example, the conductive material is depositedon the seed layers 138-1, 138-2, 138-3 and is thus adhered to thedielectric material 131. However, because the portions surrounding theelectrically conductive traces 140-1, 140-2, 140-3 are masked, theconductive material is not deposited in those locations.

FIG. 3E depicts the conductive flexible framework 130 coated with thedielectric 131 and the electrically conductive traces 140-1, 140-2,140-3, according to various embodiments of the present disclosure. Insome embodiments, the masked portion 134 can be stripped, leaving theelectrically conductive traces 140-1, 140-2, 140-3 exposed on thedielectric material 131 that coats the conductive flexible framework130. In an example, the dielectric material 131 can insulate theelectrically conductive traces 140-1, 140-2, 140-3 from the conductiveflexible framework 130, thus preventing shorts from occurring betweenthe electrically conductive traces 140-1, 140-2, 140-3.

FIG. 3F depicts the conductive flexible framework 130 coated with anadditional layer of dielectric material 141, according to variousembodiments of the present disclosure. The additional layer ofdielectric material 141 can be deposited over the initial layer ofdielectric material 131 and over the electrically conductive traces140-1, 140-2, 140-3. In some embodiments, the additional layer ofdielectric material 141 may only be deposited on the side of theconductive flexible framework 130 upon which the electrically conductivetraces 140-1, 140-2, 140-3 are disposed.

FIG. 3G depicts the conductive flexible framework 130 after theadditional layer of dielectric material 141 has been stripped from adistal portion of each of the electrically conductive traces 140-1,140-2, 140-3, leaving an exposed area 142-1, 142-2, 142-3. In someembodiments, laser ablation can be used to strip the distal portion ofeach of the electrically conductive traces 140-1, 140-2, 140-3 to createthe exposed area 142-1, 142-2, 142-3. In some embodiments, theadditional layer of dielectric material can be removed via laserablation. In some embodiments, the exposed area 142-1, 142-2, 142-3 canbe formed using photo-definable dielectric materials, wherein theexposed area 142-1, 142-2, 142-3 is masked and the dielectric materialis patterned over the masked area. The photo-definable dielectricmaterial can be developed and the masked material can be stripped togenerate the exposed area 142-1, 142-2, 142-3.

FIG. 3H depicts mask defined areas 143-1, 143-2, 143-3 on the conductiveflexible framework 130, according to various embodiments of the presentdisclosure. In some embodiments, a mask material (e.g., masked portions144-1, 144-2, 144-3) can be a photo-definable mask material, wherein themask material can be patterned over the masked portions 144-1, 144-2,144-3 and developed to generate the masked portions 144-1, 144-2, 144-3.The masked portions can be located proximally and distally with respectto the distal portion of each of the plurality of conductive traces140-1, 140-2, 140-3 (and the exposed areas 142-1, 142-2, 142-3) to formthe mask defined areas 143-1, 143-2, 143-3.

FIG. 3I depicts seed layers 145-1, 145-2, 145-3 deposited on the maskdefined areas 143-1, 143-2, 143-3, according to various embodiments ofthe present disclosure. As previously discussed, the seed layers 145-1,145-2, 145-3 can be deposited within the mask defined areas. In someembodiments, the seed layers 145-1, 145-2, 145-3 can include copper(Cu), nickel (Ni), aluminum (Al), etc. The seed layers 145-1, 145-2,145-3 can provide a base layer upon which a layer of conductive materialcan be deposited. In an example, the seed layers 145-1, 145-2, 145-3 canprovide an interface between the additional layer of dielectric material141 and the distal portion of the electrically conductive traces 140-1,140-2, 140-3 and subsequently applied conductive material that forms themicroelectrodes 102. For instance, the seed layer can allow for theconductive material that forms the microelectrodes to be adhered to theadditional dielectric material 141. And the distal portion of theelectrically conductive traces 140-1, 140-2, 140-3.

FIG. 3J depicts microelectrodes 146-1, 146-2, 146-3 that have beenformed on the conductive flexible framework 130 via a plating process,according to various embodiments of the present disclosure. In someembodiments, the seed layers 145-1, 145-2, 145-3 can be plated with aconductive material to form the microelectrodes 146-1, 146-2, 146-3. Theconductive material that is used to form the microelectrodes 146-1,146-2, 146-3 can include platinum iridium (Pt—Ir) in some embodiments.The platinum iridium coating process can be performed as described inRao, Chepuri R. K. and Trivedi, D. C., Chemical and electrochemicaldepositions of platinum group metals and their applications,Coordination Chemistry Reviews, 249, (2005) pp 613-631; Sheela G., etal., Electrodeposition of Iridium, Bulletin of Electrochemistry, 15(5-6) May-June 1999, pp 208-210; Wu, Feng, et al., Electrodeposition ofPlatinum-Iridium Alloy on Nickel-Base Single-Crystal Superalloy TMS75,Surface and Coatings Technology Volume 184, Issue 1, 1 Jun. 2004;Baumgartner, M. E. and Raub, Ch. J., The Electrodeposition of Platinumand Platinum Alloys, Platinum Metals Review, 1988, 32, (4), 188-197;Ohno, Izumi, Electroless Deposition of Palladium and Platinum, ModernElectroplating, 5th Edition, Edited by Mordechay Schlesinger and MilanPaunovic, Copyright 2010, John Wiley & Sons, Inc. Chp 20, 477-482;Electroplating the Platinum Metals—A RECENT SURVEY OF PROCESSES ANDAPPLICATIONS, Platinum Metals Rev., 1970, 14, (3) pp 93-94; and/orYingna Wu et al., Characterization of Electroplated Platinum-IridiumAlloys on the Nickel-Base Single Crystal Superalloy, MaterialsTransactions, Vol. 46, No. 10 (2005) pp 2176-2179, which are herebyincorporated by reference.

In some embodiments, the conductive material can be platedcircumferentially around the flexible framework 130. For example, theconductive material can extend circumferentially around one of the firstand second inboard arm understructures 121, 122. As such, the seedlayers 145-1, 145-2, 145-3, as well as the masked portions 144-1, 144-2,144-3 can extend circumferentially around the first and second inboardarm understructures 121, 122, such that the conductive material can beplated circumferentially around the flexible framework 130. As such, themicroelectrodes 146-1, 146-2, 146-3 can be formed as ring electrodesthat are axial with a respective one of the first inboard armunderstructure 121 and the second inboard arm understructure 122.

FIG. 3K depicts the dielectric 131 coated conductive flexible framework130 that includes the additional layer of dielectric material 141,electrically conductive traces 140-1, 140-2, 140-3, and themicroelectrodes 146-1, 146-2, 146-3. In some embodiments, the maskedportions 144-1, 144-2, 144-3 can be stripped, thus exposing thedielectric coated electrically conductive traces 140-1, 140-2, 140-3 onthe dielectric 131 coated conductive flexible framework 130. Themicroelectrodes 146-1, 146-2, 146-3 can be electrically coupled to eachrespective electrically conductive trace 140-1, 140-2, 140-3, whileremaining insulated from one another as a result of the additionaldielectric material 141 that coats the electrically conductive traces140-1, 140-2, 140-3.

FIG. 4A depicts a top view of a processed inboard understructure 160,according to various embodiments of the present disclosure. FIG. 4Bdepicts an enlarged portion (indicated by dotted oval 4B) of a firstinboard arm 164 of the processed inboard understructure depicted in FIG.4A, according to various embodiments of the present disclosure. Asdepicted, the processed inboard understructure 160 can be have adielectric coating 161 that coats a conductive flexible framework (e.g.,conductive flexible framework 130) of the processed inboardunderstructure 160. The dielectric coating 161 can be disposed betweeneach of a plurality of patterned conductive traces 162-1, 162-2, 162-2and the conductive flexible framework. The dielectric coating 161 caninsulate the patterned conductive traces 162-1, 162-2, 162-2 from theconductive flexible framework, thus preventing a short from occurringbetween the patterned conductive traces 162-1, 162-2, 162-2. In someembodiments, a first patterned conductive trace 162-1 can beelectrically coupled to a first microelectrode 163-1; a second patternedconductive trace 162-2 can be electrically coupled to a secondmicroelectrode 163-2; and a third patterned conductive trace 162-3 canbe electrically coupled to a third microelectrode 163-3.

In some embodiments, the plurality of microelectrodes 163-1, 163-2,163-3 can be arranged in a group. For example, the plurality ofmicroelectrodes 163-1, 163-2, 163-3 disposed along the first inboard arm164 can be arranged in a respective group of three microelectrodes, asdepicted in FIG. 4A, although more or fewer than three microelectrodes163-1, 163-2, 163-3 can be arranged in a group along the first inboardarm 164. In addition, groups of microelectrodes can be arranged alongthe second inboard arm 165, along the first outboard arm, and/or alongthe second outboard arm, as depicted in FIG. 1A. In some embodiments,the high density electrode mapping catheter 101 can include more than orfewer than four arms.

The plurality of groups of microelectrodes can be arranged in respectiverows of longitudinally aligned microelectrodes that are aligned parallelto a catheter shaft longitudinal axis a′a′. In some embodiments, theplurality of patterned conductive traces 162-1, 162-2, 162-2 can bealigned parallel to the catheter shaft longitudinal axis a′a′, depictedin FIG. 1A.

FIG. 4C depicts a cross-sectional view of the first outboard arm 164along the line cc, in FIG. 4B, according to various embodiments of thepresent disclosure. FIG. 4D depicts a cross-sectional view of the firstoutboard arm 164 along line dd, in FIG. 4B, according to variousembodiments of the present disclosure. As depicted, the first outboardarm 164 includes the conductive flexible framework 165 that has beencoated with a dielectric material 166′, 166″. In some embodiments, theconductive flexible framework 165 can be coated with an upper layer ofdielectric material 166′ and a lower layer of dielectric material 166″.However, the conductive flexible framework 165 can be coatedcircumferentially with the dielectric material, as discussed herein,such that microelectrodes that are circumferentially and coaxiallydisposed around the conductive flexible framework 165 are insulated fromthe conductive flexible framework 165, preventing short circuitingbetween multiple microelectrodes disposed on the conductive flexibleframework 165.

A first patterned conductive trace 162-1 can be disposed on top of theupper layer of dielectric material 166′ and can be electrically coupledwith the first microelectrode 163-1′ via an exposed area located at adistal portion of the first patterned conductive trace 162-1, asdiscussed herein. In an example, the first microelectrode 163-1′ can becoupled to the first patterned conductive trace 162-1 by plating amasked defined area (e.g., mask defined area 145-3), as discussed inrelation to FIGS. 3I to 3K. The first microelectrode 163-1′ can contactthe exposed area 168 (e.g., exposed area 142-3) of the first patternedconductive trace 162-1, thus electrically coupling the first patternedconductive trace 162-1 with the first microelectrode 163-1′. In someembodiments, the first microelectrode 163-1′ can be electrically coupledto the exposed area 168 of the first patterned conductive trace 162-1 ata location that is proximal to a distal end 167 of the first patternedconductive trace 162-1.

As depicted in FIG. 4C, the second patterned conductive trace 162-2 (andthird patterned conductive trace 162-3, which is obscured by the secondpatterned conductive trace 162-2) can extend distally with respect tothe first microelectrode 163-1′ and can be electrically coupled with thesecond microelectrode 163-2 (and third microelectrode 163-3). The secondpatterned conductive trace 162-2 (and the third patterned conductivetrace 162-3) can be electrically insulated from the first microelectrode163-1′ via an additional layer of dielectric material 169, as discussedherein.

In some embodiments, single layers or multiple layers of patternedconductive traces can be formed on the conductive flexible framework165. For example, the processed inboard understructure 160 is depictedas including a single layer of patterned conductive traces 162-1, 162-2,162-3. However, in some embodiments, the processed inboardunderstructure 160 can multiple layers of patterned conductive traces.This can be desirable where an increased number of microelectrodes areplaced on one or more of the inboard arms and/or outboard arms; a widthof the frame is decreased, thus decreasing an area for placement of thepatterned conductive traces; and/or a width of the patterned conductivetraces is increased (e.g., due to a material selection associated withthe traces). For example, with an increased number of microelectrodes, awidth of the arms may not be sufficient such that the patternedconductive traces are adequately separated from one another to preventcross-talk and/or shorting between the patterned conductive traces. Assuch, multiple layers of patterned conductive traces can be formed onthe arms, each layer being separated from one another by a dielectricmaterial.

Connection between each patterned conductive trace and an associatedmicroelectrode can be made by filled vias, in some embodiments, forexample, as discussed in relation to FIG. 16. In some embodiments of thepresent disclosure, depending on a width of each respective arm, fivepatterned conductive traces and associated microelectrodes can be formedin a single layer of patterned conductive traces and along a single armusing a 0.001 inch line (e.g., conductive trace) and space (e.g.,spacing between the conductive traces) substrate design. For example,each of the patterned conductive traces can be 0.001 inches wide andeach patterned conductive trace can be spaced 0.001 inches away from anadjacent patterned conductive trace. In some embodiments, where agreater number of microelectrodes and/or patterned conductive traces aredesired, multiple layers of patterned conductive traces can be employedand/or additional traces can be formed on an opposite side of theconductive flexible framework, as depicted in FIG. 5.

FIG. 5 depicts a cross-sectional view of patterned conductive tracesformed on a top and bottom of a conductive flexible framework, accordingto various embodiments of the present disclosure. In some embodiments, aconductive flexible framework 180 can be coated with a dielectricmaterial, as discussed herein. The dielectric material can be disposedbetween patterned conductive traces 181-1, 181-2, 181-3, 181-4 and theconductive flexible framework 180, which can serve to insulate thepatterned conductive traces 181-1, 181-2, 181-3, 181-4 from theconductive flexible framework 180. In some embodiments, one or morepatterned conductive traces can be formed on a top of the conductiveflexible framework 180 (e.g., patterned conductive traces 181-1, 181-2)and one or more patterned conductive traces can be formed on a bottom ofthe conductive flexible framework 180 (e.g., patterned conductive traces181-3, 181-4) in a manner analogous to that discussed in relation toFIGS. 3A to 3K. Accordingly, four microelectrodes can be disposed alongthe conductive flexible framework 180. For example, a firstmicroelectrode 182 can be disposed proximally with respect to a secondmicroelectrode 183, in some embodiments.

FIG. 6A depicts the conductive flexible framework 130′ after theadditional layer of dielectric material 141′ has been stripped from adistal portion of each of the electrically conductive traces 140-1′,140-2′, 140-3′, leaving an exposed area 142-1′, 142-2′, 142-3′,according to various embodiments of the present disclosure. In anexample, process steps associated with FIGS. 3A to 3G can be performedto arrive at the embodiment depicted in FIG. 6A. In some embodiments,rather than plating the exposed areas 142-1′, 142-2′, 142-3′, solder canbe deposited on the distal portions of each of the electricallyconductive trace (e.g., traces 140-1′, 140-2′, 140-3′). For example,FIG. 6B depicts a processed conductive flexible framework 199 after theadditional layer of dielectric material 141′ has been stripped from adistal portion of each of the electrically conductive traces 140-1′,140-2′, 140-3′, leaving an exposed area 142-1′, 142-2′, 142-3′ on whichsolder 191-1, 191-2, 191-3 has been deposited, according to variousembodiments of the present disclosure. FIG. 6C depicts a cross-sectionalend view of the processed conductive flexible framework 199 depicted inFIG. 6B along the line ee.

FIG. 6D depicts a hollow cylindrical band 200, according to variousembodiments of the present disclosure. FIG. 6E depicts a hollowcylindrical band 203 in which solder 208 is deposited, according tovarious embodiments of the present disclosure. FIG. 6F depicts anisometric side and front view of the hollow cylindrical band 200depicted in FIG. 6D, according to various embodiments of the presentdisclosure. In some embodiments, the hollow cylindrical band 200 can bethe same or similar to the hollow cylindrical band 203 depicted in FIG.6E. In some embodiments, the hollow cylindrical band 200 can include asplit 201, which can extend longitudinally down a sidewall of the hollowcylindrical band. Although, as depicted in FIG. 6D (and FIG. 6F), thesplit 201 extends parallel with a longitudinal axis of the hollowcylindrical band 200, the split 201 can be divergent with thelongitudinal axis of the hollow cylindrical band 200.

In some embodiments, as depicted in FIG. 6G the hollow cylindrical band200 can be coaxially aligned with the processed conductive flexibleframework 199. In some embodiments, the hollow cylindrical band 200 canbe slipped over a proximal end of an arm of the processed conductiveflexible framework 199 into position over the solder 191-1. For example,the hollow cylindrical band 200 can be placed over the solder 191-1 suchthe solder 191-1 is aligned with the hollow cylindrical band 200 betweena proximal end and a distal end of the hollow cylindrical band 200. Insome embodiments, a circumferential width of the split 201 in the hollowcylindrical band 200 (defined by line gg in FIG. 6D) can be greater thana height of the processed conductive flexible framework (defined by lineff in FIG. 6C), such that the hollow cylindrical band 200 (e.g., theslit 201 of the hollow cylindrical band 200) can be laterally slid overthe processed conductive flexible framework 199, instead of beingslipped over a proximal end of the arm of the processed conductiveflexible framework 199.

FIG. 6H depicts a processing step associated with the hollow cylindricalband 200, according to various embodiments of the present disclosure. Insome embodiments, as discussed herein, the hollow cylindrical band 200can be coaxially aligned with the processed conductive flexibleframework 199 and the solder 191-1 can be aligned with the hollowcylindrical band 200 between a proximal end and a distal end of thehollow cylindrical band 200. The hollow cylindrical band 200 can beswaged onto the processed conductive flexible framework 199. In anexample, a force can be applied to the hollow cylindrical band 200 in adirection of at least one of the arrows (e.g., arrow 205) to swage thehollow cylindrical band 200 onto the processed conductive flexibleframework 199. FIG. 6I depicts the swaged hollow cylindrical band 206after the processing step described in relation to FIG. 6H, according tovarious embodiments of the present disclosure. As depicted, acircumferential width of the split 202 can be decreased as a result ofthe swaging process and the swaged hollow cylindrical band 206 cancontact portions of the processed conductive flexible framework 199(e.g., the corners of the processed conductive flexible framework 199and the solder 191-1).

FIG. 6J depicts the swaged hollow cylindrical band 206 and the processedconductive flexible framework 199 after a solder reflow process,according to various embodiments of the present disclosure. In anexample, a reflow process can be performed to reflow the solder depictedin FIG. 6I, such that the reflowed solder 207 is distributed andcontacts both the swaged hollow cylindrical band 206 and the processedconductive flexible framework 199. The solder 207 can connect the swagedhollow cylindrical band 206 and the processed conductive flexibleframework 199 and can electrically couple the electrically conductivetrace 140-1 and the swaged hollow cylindrical band 206. As such, theswaged hollow cylindrical band 206 forms the microelectrode, asdiscussed herein.

With reference to FIG. 6E, where solder 208 is deposited on the hollowcylindrical band 203, solder (e.g., solder 191-1) may or may not beplaced on the exposed area 142-1′, 142-2′, 142-3′ of the electricallyconductive traces 140-1′, 140-2′, 140-3′. In an example, the hollowcylindrical band 203 can be placed over the processed conductiveflexible framework 199 such that the solder 208 is in close proximity tothe exposed area 142-1′, 142-2′, 142-3′ of the electrically conductivetraces 140-1′, 140-2′, 140-3′. In some embodiments, the processing stepsdepicted and described in relation to FIGS. 6G-6J can be performed toswage the hollow cylindrical band 203 and reflow the solder 208 toestablish a connection between the hollow cylindrical band 203 and theprocessed conductive flexible framework 199 and an electrical connectionbetween the hollow cylindrical band 203 and the electrically conductivetrace 140-1′. In some embodiments, solder can be deposited on the hollowcylindrical band 203 and the exposed area 142-1′, 142-2′, 142-3′ of theelectrically conductive traces 140-1′, 140-2′, 140-3′ to allow for anincreased distribution of solder in the reflowing process.

FIG. 7A depicts a top view and end view of a second inboard arm of thehigh density electrode mapping catheter, wherein a flexible framework220 of the high density electrode mapping catheter is formed from aflexible substrate and associated processing steps, according to variousembodiments of the present disclosure (the top view is depicted abovethe end view in FIGS. 7A to 7C). In some embodiments, the flexibleframework 220 can be formed from a flexible substrate, in someembodiments. The flexible substrate can include for example, thosediscussed in relation to FIG. 11. In some embodiments, the flexiblesubstrate can include a printed circuit board. For example, the printedcircuit board can be formed from a fiberglass and/or a plastic, whichdoes not conduct electricity. In some embodiments, the printed circuitboard can be formed from a polymer. As depicted in FIG. 7A, in someembodiments, the flexible substrate 220 can be coated with a conductivematerial 222. The conductive material 222 can include Cu, for example,although other conductive materials can be used.

FIG. 7B depicts a top view and end view of the second inboard arm of thehigh density electrode mapping catheter, wherein a mask layer isdeposited on the conductive material 222 coating the flexible framework220 to form a masked trace pattern 223-1, 223-2, 223-3 on the coatedflexible framework and an unmasked portion, according to variousembodiments of the present disclosure. In an example, the surroundingareas of the masked trace pattern 223-1, 223-2, 223-3 include theuncoated conductive material 222.

FIG. 7C depicts a top view and end view of the second inboard arm of thehigh density electrode mapping catheter, wherein the surrounding areasof the masked trace pattern 223-1, 223-2, 223-3 have been stripped ofthe conductive material 222. In an example, the conductive material 222can be stripped such that the flexible substrate 220 that surrounds themasked trace pattern 223-1 is exposed. As depicted in FIG. 7C, themasked trace pattern 223-1, 223-2, 223-3 has also been stripped thusexposing electrically conductive traces 224-1, 224-2, 224-3. Theelectrically conductive traces 224-1, 224-2, 224-3 can be directlyconnected with the flexible substrate 220, which is electricallyinsulative. Accordingly, the electrically conductive traces 224-1,224-2, 224-3 can be electrically insulated from one another, thuspreventing short circuits from occurring between the electricallyconductive traces 224-1, 224-2, 224-3.

In some embodiments, as will be apparent to those of skill in the art,the embodiment depicted in FIG. 7C can be processed further using theprocessing steps depicted and described in relation to FIGS. 3E to 3Kand/or FIGS. 6A to 6J. For example, a dielectric coating can bedeposited on the electrically conductive traces 224-1, 224-2, 224-3 aswell as the flexible substrate 220 and exposed areas of the electricallyconductive traces 224-1, 224-2, 224-3 can be formed.

FIG. 8A depicts a top view of a processed inboard understructure 228,according to various embodiments of the present disclosure. FIG. 8Bdepicts an enlarged portion (indicated by dotted oval 8B) of a firstinboard arm 230 of the processed inboard understructure 228 depicted inFIG. 8A, according to various embodiments of the present disclosure. Theprocessed inboard understructure 228 includes a first inboard arm 230and a second inboard arm 231. The processed inboard understructure 228can be formed from a flexible substrate, in some embodiments, asdiscussed herein. For example, the flexible substrate include a printedcircuit board and/or polymer, in some embodiments. The flexiblesubstrate can be coated with a dielectric material 232, in someembodiments.

The first inboard arm 230 of the processed inboard understructure 228includes electrically conductive traces 224-1, 224-2, 224-3 andmicroelectrodes 227-1, 227-2, 227-3. A first electrically conductivetrace 224-1 can be electrically coupled to a first microelectrode 227-1;a second electrically conductive trace 224-2 can be electrically coupledto a second microelectrode 227-2; and a third electrically conductivetrace 224-3 can be electrically coupled to a third microelectrode 227-3.The second inboard arm 231 of the processed inboard understructure 228includes electrically conductive traces 226-1, 226-2, 226-3 andmicroelectrodes 229-1, 229-2, 229-3. A first electrically conductivetrace 226-1 can be electrically coupled to a first microelectrode 229-1;a second electrically conductive trace 226-2 can be electrically coupledto a second microelectrode 229-2; and a third electrically conductivetrace 226-3 can be electrically coupled to a third microelectrode 229-3.

FIG. 8C depicts an enlarged portion (indicated by dotted oval 8C) of thefirst inboard arm 230 of the processed inboard understructure 228depicted in FIG. 8A, according to various embodiments of the presentdisclosure. In an example, FIG. 8C depicts the first electricallyconductive trace 224-1 electrically coupled to a first proximaltermination contact pad 235-1; the second electrically conductive trace224-2 electrically coupled to a second proximal termination contact pad235-2; and the third electrically conductive trace 224-3 electricallycoupled to a third proximal termination contact pad 235-3. The proximaltermination contact pads are not depicted in FIG. 8A. In someembodiments, the flexible framework of the flexible tip portion 110 ofthe high density electrode mapping catheter 101 can include the proximaltermination contact pads. For example, each arm of the inboardunderstructure and/or each arm of the outboard understructure (and/oradditional understructures not shown) can include the proximaltermination contact pads along a proximal portion of the inboardunderstructure and/or outboard understructure.

In some embodiments, the proximal termination contact pads 235-1, 235-2,235-3 can provide electrical connection points for electricallyconnecting the microelectrodes (e.g., microelectrodes 227-1, 227-2,227-3). For example, the proximal termination contact pads 235-1, 235-2,235-3 can provide an increased area for an electrical connection to bemade with each of the electrically conductive traces 224-1, 224-2, 224-3and thus each of the microelectrodes 227-1, 227-2, 227-3. In someembodiments, the proximal termination contact pads 235-1, 235-2, 235-3can be used to electrically test continuity between each of theelectrically conductive traces and respective microelectrodes. Forexample, each of the proximal termination contact pads can be probedwith an electrical testing device to ensure that an uninterruptedelectrical connection exists between each of the proximal terminationcontact pads, a respective one of the electrically conductive traces,and a respective microelectrode. In some embodiments, the proximaltermination contact pads can provide an increased area for probing withthe electrical testing device (e.g., versus proving each individualelectrically conductive trace).

FIG. 9A depicts a top view of a bottom mold 245 for an overmoldingprocess, according to various embodiments of the present disclosure. Thebottom mold 245 includes a mold cavity 246, which can be size andconfigured to accept an understructure (e.g., processed understructure)of the flexible tip portion 110. In some embodiments, different moldscan be used for the outboard understructure and the inboardunderstructure (and additional understructures if included). In someembodiments, the bottom mold 245 can be sized and configured to acceptthe processed inboard understructure 160 and/or the processed inboardunderstructure 228 in the mold cavity 246, as depicted in FIG. 9B.

FIG. 9B depicts a top view of a processed inboard understructure 228inserted into the bottom mold 245, according to various embodiments ofthe present disclosure. In an example, the processed inboardunderstructure 228 depicted in FIG. 8A is depicted as being inserted inthe mold cavity 246 of the bottom mold 245. FIG. 9C depicts across-sectional side view of an assembled mold 250 along line hh in FIG.9B, according to various embodiments of the present disclosure.

FIG. 9C depicts a top mold 247 and the bottom mold 245 in a closedposition, thus enclosing the processed inboard understructure 228(consisting of distal portion 228-1 of the processed inboardunderstructure 228 and proximal portion 228-2 of the processed inboardunderstructure 228) in the mold cavity and forming assembled mold 250.In an example, the assembled mold 250 includes a bottom mold cavity 246.The cross-sectional view of the bottom mold cavity 246 depicts a distalbottom mold cavity 246-1 and a proximal bottom mold cavity 246-2. Thebottom mold cavity 246 can be formed in the bottom mold 245. In anexample, the assembled mold 250 includes a top mold cavity 248. Thecross-sectional view of the top mold cavity 248 depicts a distal topmold cavity 248-1 and a proximal top mold cavity 248-2. The top moldcavity 248 can be formed in the top mold 247 of the assembled mold 250.

In some embodiments, the bottom mold 245 and the top mold 247 caninclude standoffs (not shown) that extend into the bottom mold cavity246 and the top mold cavity 248 to position the processed inboardunderstructure 228 a particular distance away from walls of the bottommold 245 and the top mold 247 that form the bottom mold cavity 246 andthe top mold cavity 248. In an example, the distance between theprocessed inboard understructure 228 and the walls of the bottom mold245 and the top mold 247 can define a thickness of an overmolding thatcovers the understructure.

In some embodiments, the top mold 247 and/or the bottom mold 245 caninclude a port 249 configured for introduction of an overmoldingmaterial into the bottom mold cavity 246 and the top mold cavity 248. Insome embodiments, the assembled mold 250 can include a gate and runnersystem to help with distribution of the overmolding material into thebottom mold cavity 246 and the top mold cavity 248. The gate and runnersystem can be designed in accordance with rheological properties of anovermolding material.

FIG. 9D depicts a top view of bottom mold 245 and an overmolded inboardunderstructure 260 after an overmolding process has been performed,according to various embodiments of the present disclosure. FIG. 9Edepicts a cross-sectional side view of an assembled mold and theovermolded inboard understructure in FIG. 9D along line ii in FIG. 9D,according to various embodiments of the present disclosure. As depicted,the processed inboard understructure 228 has been overmolded with anovermolding material 261. The overmolding material 261 is injected viathe port 249 and fills the space existing between the processed inboardunderstructure 228 and the walls of the bottom mold 245 and the top mold247 (e.g., assembled mold 250). In some embodiments, the overmoldingmaterial 261 can include a polyether block amide (e.g., PEBAX® availablefrom Arkema). In some embodiments, the overmolding material can be apolyurethane (e.g., Pellethane 2363-80A or 2363-90A, or Tecoflex EG93Aor EG100A both available from Lubrizol Corp.) or other suitablematerials having the required biocompatibility, elastomeric, andmechanical properties required by specific design and end-userequirements.

FIG. 10A depicts a cross-sectional side view of an ablation fixture 270in which the overmolded inboard understructure 260 has been placed,according to various embodiments of the present disclosure. As depicted,the microelectrodes 229-1, 229-2, 229-3 have been overmolded with theovermolding material 261. In some embodiments, the ablation fixture 270can include an ablation reference point 271, which can be referenced byan ablation tool, in some embodiments. Although a location of theablation reference point 271 is depicted as being proximal to theovermolded inboard understructure 260, the reference point 271 can belocated distally with respect to the overmolded inboard understructure260, and/or to either side of the overmolded inboard understructure 260.The ablation tool can be a laser and/or other type of ablation tool, insome embodiments, which can reference the reference point 271 such thatthe overmolding material 261 covering (e.g., covering an outer surfaceof) the microelectrodes 229-1, 229-2, 229-3 can be accurately removed bythe ablation tool.

In some embodiments, and as depicted, the reference point 271 can belocated a particular distance away from each of the microelectrodes,represented by line jj, line kk, and line 11. In some embodiments, theablation tool can ablate the overmolding material 261 proximally and/ordistally with respect to an end point of each of the lines to remove theovermolding material 261 from the outer surface of the microelectrodes229-1, 229-2, 229-3. In some embodiments, the ablation tool can beprogrammed to ablate at specific locations based on programmableinstructions. For example, a processor (e.g., computer) can executecomputer executable instructions stored on a non-transitory computerreadable medium to cause the ablation tool to ablate at specificlocations.

FIG. 10B depicts a top view of the ablation fixture 270 in FIG. 10Aafter an ablation processing step has been completed and an ablatedovermolded inboard understructure 280, according to various embodimentsof the present disclosure. As depicted, the overmolding material 261 hasbeen removed from the microelectrodes 227-1, 227-2, 227-3, 229-1, 229-2,229-3, thus exposing the microelectrodes 227-1, 227-2, 227-3, 229-1,229-2, 229-3. In some embodiments, overmolding material 261 can beremoved from the proximal termination contact pads 235 in a similarmanner. In some embodiments, a first side of the overmolded inboardunderstructure 260 can be ablated and can then be turned over so asecond side of the partially ablated inboard understructure can beablated. Thus, the overmolding material 261 can be circumferentiallyremoved from the overmolded inboard understructure 260. FIG. 10C depictsa top view of the ablated overmolded inboard understructure 280 afterbeing ejected from the ablation fixture 270, according to variousembodiments of the present disclosure.

FIG. 11 depicts mechanical properties of various materials that can beused for forming understructures of the flexible tip portion 110,according to various embodiments of the present disclosure. In someembodiments, as discussed herein, the understructure can be formed froma flexible material. In some embodiments, the flexible material can be asuper elastic material, such as Nitinol. Examples of Nitinol can includeNitinol available from NDC; Cu doped Nitinol available from JohnsonMatthey Medical Components; Nitinol available from Fort Wayne Metals;and/or Nitinol available from Euroflex.

In some embodiments, the flexible material forming the understructurecan include a flexible substrate. In some embodiments, theunderstructures of the flexible tip portion 110 can be formed from aflexible substrate, such as a polymer and/or printed circuit board, asdiscussed herein. In some embodiments, the flexible substrate can havemechanical properties that are similar to Nitinol. For example, theflexible substrate can have an elastic modulus that is the same orsimilar to Nitinol; an ultimate tensile strength that is the same orsimilar to Nitinol; a loading plateau that is the same or similar toNitinol; and/or a flexural strength that is the same or similar toNitinol. In some embodiments, the flexible substrate can include aliquid crystalline polymer (LCP) circuit material, such as Ultralam3850HT available from Rogers Corporation; a glass microfiber reinforcedpolytetrafluoroethylene (PTFE) composite such as RT/Duroid® 5870/5880available from Rogers Corporation; a glass-reinforced epoxy laminate(FR4) in accordance with IPC 4101C/21/24/26/121/124/129; aglass-reinforced epoxy laminate (FR4) in accordance withCharacterization of the material properties of two FR4 printed circuitboard laminates, E. T. Haugan and P. Dalsjo, Norwegian Defense ResearchEstablishment (FFI), Report 10 Jan. 2014; S1141 available from ShengyiSci. Tech. Co. Ltd.; FR408HR available from Isola Group; aBismaleimide/Triazine (BT) and epoxy resin blend such as BT G200available from Isola; and/or a Bismaleimide/Triazine (BT) and epoxyresin blend such as N5000-32 available from Nelco®.

In some embodiments, the flexible tip portion 110 depicted in FIGS. 1Aand 1B can have an array buckling force of less than or equal to 200grams of force. For example, to cause the flexible tip portion 110 todeflect, an amount of force less than or equal to 200 grams of force canbe applied to the flexible tip portion. For instance, the flexible tipportion can be deflected as shown in FIG. 1B when an amount of forceless than or equal to 200 grams of force has been applied to a distalend of the flexible tip portion, which can be formed from the materialsdiscussed herein.

FIG. 12A depicts a top view of a proximal end of an inboardunderstructure 290, according to various embodiments of the presentdisclosure. In some embodiments, the inboard understructure 290 caninclude frame locks 291-1, 291-2, 291-3, 291-4 on the proximal end ofthe inboard understructure 290. It should be noted that an outboardunderstructure can include frame locks that correspond with frame locks291-1, 291-2, 291-3, 291-4 on the inboard understructure.

FIG. 12B depicts a top view of an enlarged portion (indicated by dottedcircle 12B) of frame locks 291-1, 291-2, 291-3, 291-4 depicted on aproximal end of the inboard understructure depicted in FIG. 12A,according to various embodiments of the present disclosure. In someembodiments, one or more electrical connections 292-1, 292-2, . . .292-8 can be disposed on one or more of the frame locks 291-1, 291-2,291-3, 291-4 and/or on one of the arms of the understructure. Forexample, the electrical connections 292-1, 292-2, . . . 292-8 can beformed on a proximal portion of the arms of the understructure.

FIG. 12C depicts a top view of an enlarged portion (indicated by dottedcircle 12C) of electrical connections 292-3, 292-4 depicted in FIG. 12B,according to various embodiments of the present disclosure. In someembodiments, a third electrical connection 292-3 can include a distalcontact pad 295-1 and a proximal contact pad 295-2 and a fourthelectrical connection 292-4 can include a distal contact pad 295-4 and aproximal contact pad 295-3. As discussed herein, the electricalconnections can be disposed on the proximal portion of an understructureof the flexible tip portion 110. In some embodiments, the electricalconnections can be insulated from the understructure (e.g., where theunderstructure is electrically conductive) to prevent short circuitingfrom occurring between the electrical connections. With reference to thefourth electrical connection 295-4, the distal contact pad 295-4 and theproximal contact pad 295-3 can be electrically couple to one another viaa trace 296-2.

FIG. 12D depicts a cross-sectional view of FIG. 12C along line mm,according to various embodiments of the present disclosure. In someembodiments, the understructure 290 can be coated with a dielectric 297material, such as parylene. The dielectric material 297 can electricallyinsulate the electrical connections from a conductive understructure290, as discussed herein. In some embodiments, a metallization can becompleted on a surface of the dielectric, thus allowing for a secureconnection between the electrical connection 292-4 to the understructure290. In an example, a metal such as aluminum can be deposited on thesurface of the dielectric material 297 and the electrical connection292-4 can be disposed on top of the metal 298.

FIG. 12E depicts a top view of wires electrically coupled via anelectrical connection depicted in 12C, according to various embodimentsof the present disclosure. In an example, a distally running wire 300and/or a proximally running wire 301 can be electrically coupled to thethird electrical connection 292-3. In some embodiments the distallyrunning wire 300 and the proximally running wire 301 can be connectedvia the third electrical connection 292-3. In an example, the distallyrunning wire 300 can be soldered to the distal contact pad 295-4 and/orthe proximally running wire 301 can be soldered to the proximal contactpad 295-3. In some embodiments where the flexible tip portion does notinclude electrically conductive traces that are electrically coupledwith each of the microelectrodes, wires (e.g., distally running wires)can be electrically coupled with each of the microelectrodes.

In some embodiments, a proximal end of the distally running wires can beelectrically coupled with distal contact pads of each of the electricalconnections. Accordingly, the flexible tip portion 110 can be formed asa module, wherein the individual distally running wires are connected ata distal end to each of the microelectrodes and at a proximal end to adistal contact pad of the electrical connections. In some embodiments,the proximal contact pad can be left open (e.g., a wire may not beelectrically coupled to the proximal contact pad) such that the modulecan be tested. For example, each of the proximal contact pads can beprobed with an electrical testing device to establish that continuityexists and that a signal noise associated with each of themicroelectrodes and associated distally running wire does not exceed adefined amount. This can be accomplished prior to assembling the entirehigh density electrode mapping catheter 101.

In contrast, some prior methods assemble the entire high densityelectrode mapping catheter 101 before testing is performed. In addition,the electrical connectors can decrease a complexity associated withconnecting the proximally running wires and the distally running wiresof the high density electrode mapping catheter 101. For example, ratherthan directly connecting the proximally and distally running wires, theproximal end of the distally running wire can be coupled with the distalpad of the electrical connection and the distal end of the proximallyrunning wire can be coupled with the proximal pad of the electricalconnection.

In some embodiments, a pre-made substrate (e.g. flex substrate) can beemployed, wherein the pre-made substrate includes the electricalconnections and can be bonded to the understructure (e.g., the parylenecoated frame). In an example, the substrate design can copy the basicelectrical connection configuration discussed and depicted in relationto FIGS. 12B to 13B. This can allow for a microelectrode density to beincreased on an array formed by the flexible tip portion 110 (e.g.increase number of microelectrodes from 22 to 32 to 64) by formingmultilayer substrates. In some embodiments, the pre-made substrate canbe attached to the understructure using adhesive materials, such asepoxy.

FIG. 13A depicts a top view of a plurality of electrical connectionsdisposed on an first inboard arm 310; second inboard arm 311, firstoutboard arm 312; and second outboard arm 313 of a flexible framework ofa flexible tip portion 110 of the high density electrode mappingcatheter 101, according to various embodiments of the presentdisclosure. The plurality of electrical connections are generallydiscussed in relation to electrical connections 314-1, 314-2, 314-3,314-4. As discussed in relation to FIGS. 12A to 12E, the electricalconnections can be disposed on frame locks (e.g., frame lock 315) and/ora proximal portion of the arms 310, 311, 312, 314. In some embodiments,a number of electrical connections disposed on each frame lock can rangefrom 1 to 10. Electrical connection density can be increased inaccordance with targeted device dimensions and pad/trace line and spacerequirements. If the design provides sufficient real estate, the numberof connections can be increased as needed. With reference to a firstelectrical connection 314-1, each of the electrical connections caninclude a proximal contact pad and a distal contact pad electricallycoupled by a trace 317. For example, the first electrical connection314-1 can include a distal contact pad 316-1 and a proximal contact pad316-2 connected by a trace 317, as discussed herein.

In some embodiments, distally extending wires, for example distallyextending wire 321 can extend distally along the flexible framework ofthe high density electrode mapping catheter 101. As depicted in FIG. 13B, a proximal end of each of the distally extending wires can beelectrically coupled to a distal contact pad (e.g., distal contact pad316-1) of each of the electrical connections. Connection of the distalend of each of the distally extending wires can result in a singlemodule that can be tested, as discussed herein.

In some embodiments, each of the arms can extend through a torsionalspacer 320, which can be configured to maintain an alignment between thearms. In some embodiments, an overmolding and ablation process can beemployed, as discussed in relation to FIGS. 9A to 10C, which canovermold each arm of the flexible framework (e.g., arms 310, 311, 312,314) as well as the torsional spacer 320. In addition, the connector108, depicted in FIGS. 1A and 1B, can be overmolded as well. In someembodiments, an overmolding material can include PEBAX® as discussedherein.

FIG. 13B depicts a top view of a portion of a subset of the electricalconnections disposed on a first inboard arm 310; second inboard arm 311,first outboard arm 312; and second outboard arm 313 of a flexibleframework of a flexible tip portion 110 of the high density electrodemapping catheter 101 depicted in FIG. 13A, according to variousembodiments of the present disclosure. The subset of electricalconnections is generally discussed in relation to electrical connections314-1, 314-2, 314-3, 314-4. In an example, a proximal end of each of aplurality of distally extending wires can be electrically coupled to arespective one of a plurality of distal contact pads of each of theplurality of electrical connections and a distal end of each of aplurality of proximally extending wires can be electrically coupled to arespective one of proximal contact pads of each of the plurality ofelectrical connections. For example, with specific reference toelectrical connection 314-2, distally extending wire 330 and proximallyextending wire 331, the proximal end of the distally extending wire 330can be electrically coupled to the distal contact pad 316-1 and thedistal end of the proximally extending wire 331 can be electricallycoupled to the proximal contact pad 316-2 of the electrical connection314-2. The contact pads 316-1, 316-2 can be electrically coupled via thetrace 317 as discussed herein, and thus the wires 330, 331 can beelectrically coupled with one another.

FIG. 14 depicts a method flow diagram 340 for a process for forming anintegrated electrode structure that includes a conductiveunderstructure, according to various embodiments of the presentdisclosure. In some embodiments, the method can include coating aflexible framework of a flexible tip portion of the integrated electrodestructure with a first dielectric material at step 331. A trace patternon the coated flexible framework can be masked with a masking materialto form a masked portion and an unmasked trace pattern portion at step332. In some embodiments, a seed layer can be deposited on the unmaskedtrace pattern portion at step 333. The method can include plating theseed layer with a conductive material to form an electrically conductivetrace at step 334. At step 335, the method can include stripping themasking material from the masked portion.

The method can include coating the electrically conductive trace with asecond dielectric material at step 336. At step 337, the method caninclude stripping the second dielectric material from a distal portionof the electrically conductive trace. The method can includeelectrically connecting a microelectrode to the distal portion of theelectrically conductive trace at step 338. Electrically connecting themicroelectrode to the distal portion of the electrically conductivetrace can include masking the flexible framework of the integratedelectrode structure proximally and distally with respect to the distalportion of the electrically conductive trace to form a mask definedarea; depositing a second seed layer across the mask defined area; andplating the mask defined area with an electrically conductive materialto form the microelectrode, as discussed herein. In some embodiments,masked portions of the flexible framework can be stripped of the maskingmaterial, as discussed herein. In some embodiments wherein themicroelectrodes are to extend circumferentially around the flexibleframework, the method can include circumferentially masking the flexibleframework of the integrated electrode structure proximally and distallywith respect to the distal portion of the electrically conductive traceto form a circumferential mask defined area.

In some embodiments, the microelectrode may not be formed through aplating process (e.g., depositing a conductive material to form themicroelectrode), rather a hollow cylindrical band can be electricallyconnected to the distal portion of the electrically conductive trace,wherein the hollow cylindrical band is coaxial with the flexibleframework of the flexible tip portion. In some embodiments, electricallyconnecting the hollow cylindrical band to the distal portion of theelectrically conductive trace can include depositing solder on thedistal portion of the electrically conductive trace; coaxially aligningthe hollow cylindrical band with the distal portion of the electricallyconductive trace and the flexible framework; and reflowing the solder toelectrically couple the hollow cylindrical band with the distal portionof the electrically conductive trace.

FIG. 15 depicts a method flow diagram 350 for a process for forming anintegrated electrode structure that includes a substrate understructure,according to various embodiments of the present disclosure. In someembodiments, the method can include coating a flexible frameworksubstrate of a flexible tip portion of the integrated electrodestructure with a conductive material at step 351. In some embodiments,the flexible framework can be formed of a flexible substrate. The methodcan include masking a trace pattern on the coated flexible frameworkwith a masking material to form a masked trace pattern portion and anunmasked portion at step 352. At step 353, the method can includeetching the unmasked portion to expose the flexible framework substrate.In some embodiments, the method can include stripping the maskingmaterial from the masked trace pattern portion to expose an electricallyconductive trace at step 354. The method can include coating theelectrically conductive trace with a dielectric material at step 355. Insome embodiments, the method can include stripping the dielectricmaterial from a distal portion of the electrically conductive trace atstep 356. At step 357, the method can include electrically connecting amicroelectrode to the distal portion of the electrically conductivetrace.

As discussed herein, the method can further include overmolding theintegrated electrode structure with a polymer such as PEBAX®, in someembodiments. The overmolding can be removed from an outer surface of themicroelectrode via a ablating step, as discussed herein, in someembodiments.

FIG. 16 depicts a side view of an arm 369 of the high density electrodemapping catheter, according to various embodiments of the presentdisclosure. In some embodiments, a dielectric material 371 can coat anunderstructure 370 of the arm 369 of the high density electrode mappingcatheter. In some embodiments, one or more electrically conductivetraces 372 can be formed on an outer facing surface of the dielectricmaterial 371 (facing away from the understructure 370), as discussedherein. For example, in a manner analogous to that discussed herein, amask can be applied to the dielectric material 371 to form unmaskedtrace pattern portions. A seed layer can be applied to coat the unmaskedtrace pattern portions. The electrically conductive trace 372 can beformed on top of the seed layer, which can adhere the electricallyconductive trace 372 to the dielectric material 371.

In some embodiments, multiple layers of electrically conductive traces372 can be formed on the arm 369 of the high density electrode mappingcatheter, as depicted in FIG. 16. One or more additional electricallyconductive traces 373 can be formed on a second layer of dielectricmaterial 374. The second layer of dielectric material 374 can be appliedover the first layer of dielectric material 371 and over theelectrically conductive trace 372. In some embodiments, a first via 375can be formed in the dielectric material 374 that coats the electricallyconductive trace 372. In an example, a mask can be applied over aportion of the electrically conductive trace 372 (e.g., a portion wherethe via 375 will be formed) before the second layer of dielectricmaterial 374 is applied and/or the second layer of dielectric material374 can be removed to create the first via 375. Additional electricallyconductive traces can be constructed in this manner.

In some embodiments, the additional electrically conductive trace 373can be applied over a portion of the second layer of dielectric material374. In an example, a distal end of the additional electricallyconductive trace can be disposed proximally with respect to the firstvia 375. In some embodiments, the additional electrically conductivetrace 373 and the electrically conductive trace 372 can run parallelwith respect to one another and parallel with respect to theunderstructure 370. In some embodiments, a third layer of dielectricmaterial 376 can coat a portion (e.g., outer facing surface) of thesecond layer of dielectric material 374 and the additional electricallyconductive trace 373. In some embodiments, a mask can be applied overthe additional electrically conductive trace 373 (e.g., a portion wherethe via 377 will be formed) before the third layer of dielectricmaterial 376 is applied and/or the third layer of dielectric material376 can be removed to create the via 377 for the second electricallyconductive trace 373.

In some embodiments, the mask applied to the electrically conductivetrace 372 can be removed after application of the third layer ofdielectric material 376, thus creating the first via 375 in the secondlayer of dielectric material 374 and a second via 378 in the third layerof dielectric material 376 to form via 379. As depicted in FIG. 16,multiple layers of electrically conductive traces 372, 373 can be formedon the understructure 370 of the arm 369. As discussed herein, this canbe beneficial when a real estate associated with a surface of the arm369 is not large enough to support formation of more than a particularnumber of electrically conductive traces next to one another.Accordingly, some embodiments of the present disclosure can allow forelectrically conductive traces to be formed in different layers.

In some embodiments, a similar formation can be formed on another sideof the understructure 370 of the arm 369. For example, another side ofthe arm 369 (e.g., opposite side of the arm 369 with respect to theelectrically conductive traces 372, 373) can include a similar formationthat supports formation of electrically conductive traces in differentlayers, as discussed herein.

FIGS. 17A to 17E depict a side view of an understructure of an arm ofthe high density electrode mapping catheter and associated processingsteps, according to various embodiments of the present disclosure. FIG.17A depicts an understructure 385-1 associated with the arm of the highdensity electrode mapping catheter. As depicted in FIG. 17B, in someembodiments, a first via 386-1 and second via 386-2 can be formed in theunderstructure 385-2. In an example, the vias 386-1, 386-2 can be cutvia a laser, drilled, etc. As depicted in FIG. 17C, in some embodiments,the understructure 385-2 can be coated with a first coating ofdielectric material 387, such as parylene, for example.

As depicted in FIG. 17D, an electrically conductive trace 388 can beapplied on the first coating of dielectric material 387 that coats theunderstructure 385-2. In some embodiments, the electrically conductivetrace 388 can be applied to a top surface and bottom surface associatedwith the first coating of dielectric material 387 that coats theunderstructure 352-2. The electrically conductive trace 388 can fill thevia 386-2, thus electrically coupling a bottom portion of theelectrically conductive trace 388 applied to the bottom surfaceassociated with the first coating of dielectric material 387 and a topportion of the electrically conductive trace 388 applied to the topsurface associated with the first coating of dielectric material 387. Insome embodiments, the electrically conductive trace 388 can extendproximally with respect to the via 386-2. In some embodiments, theelectrically conductive trace 388 can extend distally with respect tothe second via 386-2. For example, and as depicted in FIG. 17D, a distalend of the electrically conductive trace 388 can be disposed between thefirst via 386-1 and the second via 386-2.

As depicted in FIG. 17E, a second coating of dielectric material 390 canbe applied to a top surface and bottom surface of the first coating ofdielectric material 387 and the electrically conductive trace 388. Insome embodiments, the second coating of dielectric material 390 may notbe applied to the first via 386-1 and/or can be removed from the firstvia 386-1. FIG. 17F depicts a processed understructure 392 that includesa second electrically conductive trace 391 applied to a top surface andbottom surface of the second coating of dielectric material 390. In someembodiments, as depicted in FIG. 17F, the second electrically conductivetrace 391 can be applied to the portions of the first coating ofdielectric material 387 surrounding the first via 386-1, that are notcoated with the second coating of dielectric material 390. In anexample, the second coating of dielectric material 390 can be appliedproximally and/or distally with respect to the first via 386-1, leavingthe first coating of dielectric material 387 exposed for coating withthe second electrically conductive trace 391. The second electricallyconductive trace 391 can extend along a top portion and a bottom portionof processed understructure 392. The second electrically conductivetrace 391 can extend through the via 386-1, thus electrically couplingportions of the second electrically conductive trace 391 extending alongthe top portion and the bottom portion of the processed understructure392.

In some embodiments, the first electrically conductive trace 388 can belaterally offset from the second electrically conductive trace 391. Assuch, a via can be formed in the second coating of dielectric material390, which can be used to electrically connect a microelectrode or otherdevice to the first electrically conductive trace 388, whileelectrically insulating the microelectrode or other device from thesecond electrically conductive trace 391. In some embodiments, a thirdcoating of dielectric material can be applied to the second electricallyconductive trace 391 and a microelectrode can be electrically coupledwith the second electrically conductive trace 391 through a via formedin the third coating of dielectric material.

FIGS. 18A to 18G depict top views of embodiments of an understructure ofa high density electrode mapping catheter in FIG. 1A, according tovarious embodiments of the present disclosure. The embodiments depictedin FIGS. 18A to 18G can be constructed from a unitary piece of material.For example, FIG. 18A depicts an understructure 410 that includes aninner understructure 411 (also referred to herein as inboardunderstructure) and an outer understructure 412 (also referred to hereinas outboard understructure), which can be formed from a single piece ofmaterial. In some embodiments, the inner understructure 411 and theouter understructure 412 can be laser cut from a single piece ofmaterial and/or photo etched from a single piece of material.

As depicted in FIG. 18A, a distal end of the inner understructure 411can be connected to a distal end of the outer understructure 412 via aconnective portion 413. The connective portion 413 can be formed fromthe same unitary piece of material as the inner understructure 411 andthe outer understructure 412. The connective portion 413 can extend froma distal side of the distal end of the inner understructure 411 to aproximal side of the distal end of the outer understructure 412. In someembodiments, the connective portion 413 can be planar and can be equalin thickness with the inner understructure 411 and the outerunderstructure 412. The connective portion can extend between the distalend of the inner understructure 411 and the distal end of the outerunderstructure 412 on either side of an understructure longitudinal axisnn defined by the inner understructure 411 and the outer understructure412, which is depicted in FIG. 18A.

As depicted in FIG. 18A, outer edges 415-1, 415-2 can be radiused towardthe understructure longitudinal axis nn. In some embodiments, theradiused outer edges 415-1, 415-2 can help with minimizing strainexisting between the inner understructure 411 and the outerunderstructure 412, as the understructure 410 is inserted and/ordeployed from a sheath. For example, in some embodiments where the outeredges are straight, and are not radiused, the portions of the innerunderstructure 411 and the outer understructure 412 located adjacent tothe outer edges of the connective portion 413 can experience anincreased strain. In contrast, the radiused outer edges 415-1, 415-2 canbetter distribute the strain as the understructure 410 is deflectedand/or inserted into or deployed from the sheath.

FIG. 18B depicts an embodiment of an understructure 420 that includes aninner understructure 421 and an outer understructure 422. As depicted inFIG. 18B, a distal end of the inner understructure 421 can be connectedto a distal end of the outer understructure 422 via a connective portion423. The connective portion 423 can be formed from a same unitary pieceof material as the inner understructure 421 and the outer understructure422. The connective portion 423 can extend from a distal side of thedistal end of the inner understructure 421 to a proximal side of thedistal end of the outer understructure 422, in some embodiments.

In some embodiments, the connective portion 423 can be planar and can beequal in thickness with the inner understructure 421 and the outerunderstructure 422. The connective portion 423 can extend between thedistal end of the inner understructure 421 and the distal end of theouter understructure 422 on either side of an understructurelongitudinal axis oo defined by the inner understructure 421 and theouter understructure 422, which is depicted in FIG. 18B. In contrast toFIG. 18A, the connective portion 423 may not extend as far to eitherside of the understructure longitudinal axis oo for reasons discussedherein. As discussed in relation to FIG. 18A, the connective portion caninclude radiused outer edges 425-1, 425-2, which can better distributestrain between the inner understructure 421, the connective portion 423,and the outer understructure 422, as the understructure 420 is deflectedand/or inserted into or deployed from a sheath. In some embodiments,because the connective portion 423 does not extend as far to either sideof the understructure longitudinal axis oo, the understructure may bedeflected with less force, in some embodiments, and/or can be introducedand/or deployed from a sheath more easily.

In some embodiments, the understructure 420 can include first and secondouter connective members 426-1, 426-2, which connect a flared distalhead 427 of the inner understructure 421 to the outer understructure422. For example, the flared distal head 427 can include a first flaredsegment 428-1 that is flared away from the understructure longitudinalaxis oo and a second flared segment 428-2 that is flared away from theunderstructure longitudinal axis oo. In some embodiments, a first outerconnective member 426-1 can connect the first flared segment 428-1 tothe outer understructure 422 and a second outer connective member 426-2can connect the second flared segment 428-2 to the outer understructure422. The first and second outer connective members 426-1, 426-2 canconnect with the outer understructure 422 at points on the outerunderstructure that are adjacent to a respective one of the first flaredsegment 428-1 and the second flared segment 428-2.

In some embodiments, the first connective member 426-1 can be flaredtowards the connective portion 423 and the second connective member426-2 can be flared towards the connective portion 423, in someembodiments. Alternatively, the first and second connective members426-1, 426-2 can be flared away from the connective portion 423. Byflaring the connective members 426-1, 426-2, the members can belengthened or shortened as the understructure is deflected and/orinserted into or deployed from a sheath (e.g., slack can built into theconnective members 426-1, 426-2). For example, as the understructure 420is introduced into a sheath, the outer understructure 422 can becompressed towards the understructure longitudinal axis oo, causing anincrease in axial length. To compensate for this increase in axiallength, the flared distal head 427 can straighten (become less flared)as the outer understructure 422 is compressed and lengthened. This caneffectively increase a length of the inner understructure 421, andprevent the inner understructure 421 from pulling on the outerunderstructure 422, thus preventing the outer understructure 422 fromhooking within the sheath. As the inner understructure 421 straightensand elongates, the first and second connective members 426-1, 426-2 canstraighten (become less flared) and elongate to allow the outerunderstructure 422 to elongate. In some embodiments, as the outerunderstructure 422 is compressed, the first and second connectivemembers 426-1, 426-2 can help pull the first and second flared segments428-1, 428-2 of the flared distal head 427 and cause the flared distalhead 427 to elongate with the outer understructure 422.

FIG. 18C depicts an understructure 430 that includes an innerunderstructure 431 and an outer understructure 432, which can be formedfrom a single piece of material. In some embodiments, the innerunderstructure 431 and the outer understructure 432 can be laser cutfrom a single piece of material and/or photo etched from a single pieceof material. As depicted in FIG. 18C, a distal end of the innerunderstructure 431 can be connected to a distal end of the outerunderstructure 432 via a connective portion 433. The connective portion433 can be formed from the same unitary piece of material as the innerunderstructure 431 and the outer understructure 432. The connectiveportion 433 can extend from a distal side of the distal end of the innerunderstructure 431 to a proximal side of the distal end of the outerunderstructure 432. In some embodiments, the connective portion 433 canbe planar and can be equal in thickness with the inner understructure431 and the outer understructure 432. The connective portion 433 canextend between the distal end of the inner understructure 431 and thedistal end of the outer understructure 432 on either side of anunderstructure longitudinal axis pp defined by the inner understructure431 and the outer understructure 432, which is depicted in FIG. 18C.

As depicted in FIG. 18C, the connective portion 433 can extend from theunderstructure longitudinal axis pp to an outermost portion of the firstand second flared segments 436-1, 436-2. In some embodiments, theconnective portion 433 can extend from the understructure longitudinalaxis pp to a point that is distal of the outermost portion of the firstand second flared segments 436-1, 436-2, as depicted in FIG. 18C. Theconnective portion 433 can include radiused outer edges 435-1, 435-2,which can better distribute strain as the understructure 430 isdeflected and/or inserted into or deployed from a sheath, as discussedin relation to FIG. 18A.

FIG. 18D depicts an understructure 440 that includes an innerunderstructure 441 and an outer understructure 442, which can be formedfrom a single piece of material. In some embodiments, the innerunderstructure 441 and the outer understructure 442 can be laser cutfrom a single piece of material and/or photo etched from a single pieceof material. As depicted in FIG. 18D, a distal end of the innerunderstructure 441 can be connected to a distal end of the outerunderstructure 442 via connective portions 443-1, 443-2. The connectiveportions 443-1, 443-2 can be formed from the same unitary piece ofmaterial as the inner understructure 441 and the outer understructure442. The connective portions 443-1, 443-2 can extend from a distal sideof the distal end of the inner understructure 441 to a proximal side ofthe distal end of the outer understructure 442. In some embodiments, theconnective portions 443-1, 443-2 can be planar and can be equal inthickness with the inner understructure 441 and the outer understructure442. The connective portions 443-1, 443-2 can extend between the distalend of the inner understructure 441 and the distal end of the outerunderstructure 442 on either side of an understructure longitudinal axisqq defined by the inner understructure 441 and the outer understructure442, which is depicted in FIG. 18D.

As depicted in FIG. 18D, a first connective portion 443-1 can extendbetween a first distally angled segment 448-1 of the innerunderstructure 441 and a corresponding segment of the outerunderstructure 442. A second connective portion 443-2 can extend betweena second distally angled segment 448-2 of the inner understructure 441and a corresponding segment of the outer understructure 442. In someembodiments, a side of the first connective portion 443-1 locatedtowards the understructure longitudinal axis qq can include an inneredge 444-1 radiused away from the understructure longitudinal axis qqand a side of the second connective portion 443-2 located towards theunderstructure longitudinal axis qq can include an inner edge 444-2radiused away from the understructure longitudinal axis qq, such that agap 449 is defined between the inner edges 444-1, 444-1 of theconnective portions 443-1, 443-2 and distal ends of the inner and outerunderstructures 441, 442. In some embodiments, the gap 449 can allow forbetter flexibility of the understructure 440 as it is deflected and/orinserted into or deployed from a sheath. In some embodiments, theconnective portions 443-1, 443-2 can include outer edges 445-1, 445-2that are radiused towards the distal end of the understructure 440, asdiscussed in relation to FIG. 18A. The radiused inner edges 444-1, 444-2and radiused outer edges 445-1, 445-2 can better distribute strain, asdiscussed herein.

FIG. 18E depicts an embodiment of an understructure 450 that includes aninner understructure 451 and an outer understructure 452. In someembodiments, the understructure 450 can include first and second outerconnective members 456-1, 456-2, which connect a flared distal head 457of the inner understructure 451 to the outer understructure 452. Forexample, the flared distal head 457 can include a first flared segment458-1 that is flared away from the understructure longitudinal axis rrand a second flared segment 458-2 that is flared away from theunderstructure longitudinal axis rr. In some embodiments, a first outerconnective member 456-1 can connect the first flared segment 458-1 tothe outer understructure 452 and a second outer connective member 456-2can connect the second flared segment 458-2 to the outer understructure452. The first and second outer connective members 456-1, 456-2 canconnect with the outer understructure 452 at points on the outerunderstructure 452 that are adjacent to a respective one of the firstflared segment 458-1 and the second flared segment 458-2.

In some embodiments, the first connective member 456-1 can be flaredtowards the distal ends of the inner and outer understructures 451, 452and the second connective member 456-2 can be flared towards the distalends of the inner and outer understructures 451, 452, in someembodiments. Alternatively, the first and second connective members456-1, 456-2 can be flared away from the distal ends of the inner andouter understructures 451, 452. By flaring the connective members 456-1,456-2, the members can be lengthened or shortened as the understructure450 is deflected and/or inserted into or deployed from a sheath, asdiscussed herein.

FIG. 18F depicts an embodiment of an understructure 460 that includes aninner understructure 461-1, 461-2 and an outer understructure 462. Insome embodiments, the understructure 460 can include first and secondouter connective members 466-1, 466-2, which connect a flared distalhead 467 of the inner understructure 461-1, 461-2 to the outerunderstructure 462. In contrast to FIG. 18E, the inner understructure461-1, 462-2 can be terminated at a first flared segment 468-1 and asecond flared segment 468-2 and may not extend distally from the firstand second flared segments 468-1, 468-2. The inner understructure 461-1,461-2, as depicted, extends proximally from the first and second flaredsegments 468-1, 468-2. In some embodiments, a first outer connectivemember 466-1 can connect the first flared segment 468-1 to the outerunderstructure 462 and a second outer connective member 466-2 canconnect the second flared segment 468-2 to the outer understructure 462.The first and second outer connective members 466-1, 466-2 can connectwith the outer understructure 462 at points on the outer understructure462 that are adjacent to a respective one of the first flared segment468-1 and the second flared segment 468-2.

In some embodiments, the first connective member 466-1 can be flaredtowards the distal ends of the inner and outer understructures 461-1,461-2, 462 and the second connective member 466-2 can be flared towardsthe distal ends of the inner and outer understructures 461-1, 461-2,462, in some embodiments. Alternatively, the first and second connectivemembers 466-1, 466-2 can be flared away from the distal ends of theinner and outer understructures 461-1, 461-2, 462. By flaring theconnective members 466-1, 466-2, the members can be lengthened orshortened as the understructure 460 is deflected and/or inserted into ordeployed from a sheath, as discussed herein.

FIG. 18G depicts an embodiment of an understructure 470 that includes aninner understructure 471-1, 471-2 and an outer understructure 472. Insome embodiments, a first and second arm of the inner understructure471-1, 472-2 can extend distally from a proximal end of theunderstructure 470. A distal portion of the first and second arms of theinner understructure 471-1, 472-2 can extend parallel to aunderstructure longitudinal axis tt and can be terminated proximallywith respect to a respective one of first and second radiused segments473-1, 473-2 of the outer understructure 472. In some embodiments,connective arms 474-1, 474-2, . . . 474-6 can extend from the first andsecond arms of the inner understructure 471-1, 472-2 transversely to andaway from the understructure longitudinal axis tt towards the outerunderstructure 472. The connective arms 474-1, 474-2, . . . 474-6 can beconnected with the inner understructure 471-1, 471-2 and the outerunderstructure 472.

FIG. 19A depicts a top view of a flexible tip portion 500 of a highdensity electrode mapping catheter that includes a plurality ofmicroelectrodes 502-1, 502-2, . . . , 502-16, according to variousembodiments of the present disclosure. Hereinafter the plurality ofmicroelectrodes 502-1, 502-2, . . . , 502-16 are referred to in theplural as microelectrodes 502 (also referred to herein as electrodes).In some embodiments, the flexible tip portion 500 forms a flexible arrayof microelectrodes 502, which can be disposed at a distal end of acatheter shaft. This planar array (or ‘paddle’ configuration) ofmicroelectrodes 502 comprises four side-by-side,longitudinally-extending arms 504, 506, 508, 510, which can form aflexible framework on which the microelectrodes 502 are disposed. Thefour microelectrode-carrier arms comprise a first outboard arm 504, asecond outboard arm 510, a first inboard arm 506, and a second inboardarm 508. These arms can be laterally separated from each other. Theinboard portion of the flexible tip 500 can include a flared headportion 512 and the outboard portion of the flexible tip 500 can includea head portion 514. The first outboard arm 504 and the second outboardarm 510 can be part of an outboard understructure and the first inboardarm 506 and the second inboard arm 508 can be part of an inboardunderstructure, as previously discussed. The first and second inboardarms 506, 508, as well as the flared head portion 512, can form theinboard arm understructure that comprises an element that includes aplanar cross-section and the first and second outboard arms 504, 510, aswell as the head portion 514, can form the outboard arm understructurethat comprises an element that includes a planar cross-section. In someembodiments, the flexible tip portion 500 can be formed from a flexiblemetal, such as nitinol. In some embodiments, the flexible tip portion500 can be formed from a flexible printed circuit board. In someembodiments, the flexible tip portion 500 can include a mounting portion516. In an example, the first and second outboard arms 504, 510 and thefirst and second inboard arms 506, 508 can be connected to the mountingportion 516. In some embodiments, the mounting portion 516, the firstand second outboard arms 504, 510, the first and second inboard arms506, 508, the flared head portion 512, and the head portion 514 can allbe formed from a unitary piece of material. The mounting portion 516 canbe inserted into a distal end of a catheter shaft, in some embodiments.

In some embodiments, the flexible tip portion 500 can include aplurality of electrically conductive traces 518-1, 518-2, 518-3, 518-4disposed along the mounting portion 516, the first and second outboardarms 504, 510, the first and second inboard arms 506, 508, the flaredhead portion 512, and/or the head portion 514. Hereinafter, theelectrically conductive traces 518-1, 518-2, 518-3, 518-4 are referredto in the plural as electrically conductive traces 518. Each one of theelectrically conductive traces 518 can be electrically coupled with oneof the microelectrodes 502. For example, a first microelectrode 502-1can be electrically coupled with a first electrically conductive trace518-1, a second microelectrode 502-2 can be electrically coupled with asecond electrically conductive trace 518-2, a third microelectrode 502-3can be electrically coupled with a third electrically conductive trace518-3, and/or a fourth microelectrode 502-4 can be electrically coupledwith a fourth electrically conductive trace 518-4. Although more thanfour traces are disposed on the flexible tip portion, for clarity onlythe traces 518-1, 518-2, 518-3, 518-4 are discussed herein.

In some embodiments, the traces 518 and/or microelectrodes 502 can beformed as previously discussed herein. In some embodiments, the traces518 and/or microelectrodes 502 can be formed in a manner such as thatdiscussed in relation to FIGS. 23A to 23F. As depicted, the first trace518-1 can extend from a proximal side of the first microelectrode 502-1.In some embodiments, each of the traces 518 can be electrically coupledwith a respective one of the microelectrodes 502 through a via, asfurther discussed herein. As depicted, the microelectrodes 502 can bedisposed along a longitudinal length of each one of the arms. In someembodiments, the traces 518 can be routed around each one of themicroelectrodes 502 that the traces 518 are not electrically coupledwith to avoid contacting those microelectrodes, and thus preventing ashort from occurring. In an example and as depicted, the secondelectrically conductive trace 518-2 can be routed around the firstmicroelectrode 502-1 to avoid contact with the first microelectrode502-1. The second electrically conductive trace 518-2 can be extendalong an inner side of the first microelectrode 502-1 and can be coupledwith the second microelectrode 502-2. The third trace 518-3 can berouted around an outer side of the first microelectrode 502-1 and secondmicroelectrode 502-2 and can be coupled with the third microelectrode502-3. The fourth trace 518-4 can be routed around an inner side of thefirst microelectrode 502-1, second microelectrode 502-2, and thirdmicroelectrode 502-3 and can be coupled with the fourth microelectrode502-4. In an example, a trace associated with each longitudinallyalternating microelectrodes 502 can be routed around alternating sidesof the preceding microelectrodes 502, as depicted. For example, thesecond trace 518-2 associated with the second microelectrode can berouted on an inside of the preceding first microelectrode 502-1; thethird trace 518-3 associated with the third microelectrode 502-3 can berouted on an outside of the preceding first and second microelectrodes502-1, 502-3; and the fourth trace 518-4 associated with the fourthmicroelectrode 502-4 can be routed on an inside of the preceding firstmicroelectrode 502-1, second microelectrode 502-2, and thirdmicroelectrode 502-3. This can allow for a more even distribution of thetraces 518 on either side of the microelectrodes 502, thus allowing forthe microelectrodes 502 to be more evenly spaced in the center of eacharm.

In some embodiments, each of the traces 518 can be routed proximallyalong each one of the arms 504, 506, 508, 510 to the mounting portion516. In some embodiments, the mounting portion 516 can include aplurality of contact pads 520-1, 520-2, . . . , 520-9, hereinafterreferred to in the plural as contact pads 520, arranged in a first row522-1 and a second row 522-2. For clarity only contact pads 520-1,520-2, . . . , 520-9 are discussed. In some embodiments, a proximal endof each one of the traces 518 can terminate at a respective one of thecontact pads 520.

In some embodiments, each row of contact pads 522-1, 522-2 can bedivergent with a longitudinal axis of the flexible tip portion 500. Inan example, each row of contact pads 522-1, 522-2 can extend away fromthe longitudinal axis of the flexible tip portion 500 as the row ofcontact pads 522-1, 522-2 extends distally. Accordingly, each row ofcontact pads 522-1, 522-2 can extend laterally away from one another asthe rows extends distally. In some embodiments, each row of contact pads522-1, 522-2 can be linear. In an example, the mounting portion 516 canhave a limited lateral width. Accordingly, the contact pads 520 can belongitudinally and laterally staggered with respect to one another. Forinstance, from the distal end to the proximal end of the mountingportion 516, the contact pads 520 can be longitudinally staggered towardthe proximal end and laterally staggered toward the longitudinal axis ofthe flexible tip portion 500.

In some embodiments, the trace 518-3 can be connected to the proximalend of the contact pad 520-1. Accordingly, the contact pad 520-1 can beelectrically coupled with the microelectrode 502-3. In some embodiments,a test trace can extend proximally with respect to one or more of thecontact pads 520. For example, a test trace can extend proximally withrespect to the contact pad 520-1. The test trace can lead to a testportion (not shown) that can include a larger contact test pad, whichcan be probed with a test instrument to ensure continuity between thecontact pad 520-1, the electrical trace 518-3, and the microelectrode502-3. In some embodiments, a contact test pad can be electricallycoupled with each one of the contact pads 520 via a test trace. In someembodiments, the test traces can extend proximally from each one of thecontact pads 520. The longitudinal and lateral staggering of the contactpads 520 allow for an electrical trace to extend distally from each oneof the contact pads 520 and a test trace to extend proximally from eachone of the contact pads, as depicted.

FIG. 19B depicts an enlarged top view of a pair of contact pads 520-8,520-9 disposed on the flexible tip portion depicted in FIG. 19A,according to various embodiments of the present disclosure. In someembodiments, the contact pads 520 can be formed from an electricallyconductive material. For example, the contact pads 520 can be formedfrom copper, gold, etc. In some embodiments, the contact pads 520 canhave a lateral width of approximately 0.2 millimeters, although thecontact pads can have a smaller or larger lateral width. In someembodiments, the contact pads 520 can have a longitudinal length ofapproximately 0.45 millimeters, although the contact pads can have ashorter or longer longitudinal length. As depicted, electricallyconductive traces 518-5, 518-6 can extend distally from contact pads520-8, 520-9 and can be electrically coupled with the contact pads520-8, 520-9. For example, the electrically conductive traces 518-5,518-6 can electrically couple the contact pad 520-8 with themicroelectrode 502-8 and can electrically couple the contact pad 520-9with the microelectrode 502-12, respectively. In some embodiments, thecontact pads 520-8, 520-9 can include test traces 532-8, 532-9 thatextend proximally from each one of the contact pads 520-8, 520-9,respectively, as previously discussed. As depicted, other test traces532-4, 532-5, 532-6, 532-7, 532-8 can extend longitudinally along themounting portion 516. In some embodiments, the test traces 532 can belaterally spaced apart from one another by approximately 0.05millimeters, although the test traces can be spaced apart by a smalleror greater distance in some embodiments. In some embodiments, the testtraces can have a lateral width of approximately 0.03 millimeters,although the test traces can have a lateral width that is greater thanor less than 0.03 millimeters.

FIG. 19C depicts an enlarged top view of a microelectrode 502-1 disposedon the flexible tip portion 500 depicted in FIG. 19A, according tovarious embodiments of the present disclosure. In some embodiments, themicroelectrode 502-1 can have an electrically conductive trace 518-1that extends proximally from the microelectrode 502-1. In someembodiments, the microelectrode 502-1 can have a longitudinal length ina range from 0.1 to 5 millimeters and can have a lateral width in arange from 0.1 to 5 millimeters. However, in some embodiments, themicroelectrode 502-1 can have a longitudinal length of approximately0.92 millimeters and can have a lateral width of approximately 0.9millimeters. However, in some embodiments, the microelectrode 502-1 canhave a longitudinal length of approximately 0.92 millimeters and alateral width of approximately 0.3 millimeters. As depicted,electrically conductive traces can extend on either side of themicroelectrode 502-1, connecting other microelectrodes 502 with arespective one of the contact pads 520.

FIG. 19D depicts a side view of microelectrodes disposed on a top andbottom of the flexible tip portion 500 depicted in FIG. 19A, accordingto various embodiments of the present disclosure. FIG. 19A depicts a topof the flexible tip portion 500 with microelectrodes 502 disposed on thefirst outboard arm 504. In some embodiments, a bottom of the flexibletip portion 500 can include the same features as those of the top of theflexible tip portion 500. For example, as depicted in FIG. 19D, a bottomof the flexible tip portion 500 can also include microelectrodes 502-17,502-18, 502-19, 502-20, hereinafter referred to in the plural asmicroelectrodes 502, electrically conductive traces 518 (not shown),contact pads 520 (not shown), etc. In an example, this can enableinvestigation of different unipolar and bipolar electrogramconfigurations. In an example, where the electrodes disposed on the topof the flexible tip portion 500 are disposed against tissue and theelectrodes of the bottom of the flexible tip portion 500 are disposed ina blood pool, or vice versa, a different electrical signal can bereceived by the top electrodes than the bottom electrodes. In someembodiments, the signal (e.g., impedance) received from the topelectrodes can be analyzed with respect to the signal (e.g., impedance)received from the bottom electrodes to determine whether the flexibletip portion 500 is in contact with tissue. In some embodiments, a degreeof contact between the flexible tip portion 500 and associatedmicroelectrodes 502 and tissue can be determined based on the analysisof the signals received from the bottom electrodes and the topelectrodes. In an example, where the signals from both bottom electrodesand the top electrodes are the same, this can be an indication that theentire flexible tip portion 500 is disposed in a blood pool and is notin contact with tissue.

In an example, using this ‘bottom minus top’ bipolar configuration canresult in electrograms that are distinctly different in morphologycompared to bipolar electrograms that use a ‘bottom minus adjacentbottom’ bipolar configuration. For example, some medical devices thatare used to produce electrograms receive electrical signals fromelectrodes that are adjacent to one another and located on a same sideof the medical device. Electrograms produced with devices of the presentdisclosure, for example, those that include electrodes on both sides(e.g., top and bottom) of the device (e.g., flexible tip portion 500),can produce distinctly different electrograms.

As depicted in FIG. 19D, the microelectrodes 502 can be disposed on thetop and/or bottom of the flexible tip portion 500. For example, themicroelectrodes 502 can be disposed on a top and/or bottom of the firstoutboard arm 504, the second outboard arm 510 (FIG. 19A), the firstinboard arm 506 (FIG. 19A), and/or the second inboard arm 508 (FIG.19A). Each of the top microelectrodes 502 can have a vertically adjacentbottom microelectrode 502. In an example, a first top microelectrode502-1 can be vertically adjacent to a bottom electrode 502-17 that islocated directly beneath the first top microelectrode 502-1. In someembodiments, a vertical spacing (V_(S)) between an outer surface of eachof the microelectrodes 502 on the top and bottom of the flexible tipportion 500 can be in a range from 0 to 3 millimeters. In someembodiments, the vertical spacing (V_(S)) between an outer surface ofeach of the microelectrodes 502 on the top and bottom of the flexibletip portion 500 can approximately 0.22 millimeters. The vertical spacingV_(S) between the microelectrodes 502 disposed on the top and thosedisposed on the bottom can provide a third dimension between themicroelectrodes 502, enabling the microelectrodes 502 disposed on thetop and bottom of the flexible tip portion 500 to receive extracellularmatrix (ECM) signals.

Some medical devices can include electrodes that are disposed along asingle line, providing one-dimensional spacing, or along a plane (e.g.,that are laterally adjacent to one another), providing two-dimensionalspacing. However, embodiments of the present disclosure can providemicroelectrodes 502 that are laterally adjacent to one another and alsovertically adjacent to one another and can be configured to receive ECMsignals with both the bottom electrodes and top electrodes that arevertically adjacent to one another. In some embodiments of the presentdisclosure, the vertical spacing V_(S) between the microelectrodes 502can provide a greater resolution of extracellular matrix (ECM) signals.In addition, clean bi-pole signals can be generated between themicroelectrodes 502 disposed on the top of the flexible tip portion 500and the microelectrodes 502 disposed on the bottom of the flexible tipportion 500.

As previously discussed, a determination of whether any of themicroelectrodes on the flexible tip portion 500 are in contact withtissue can be made based on a difference in a bottom signal that isreceived by a microelectrode 502 disposed on the bottom of the flexibletip portion 500 and a top signal that is received by a microelectrode502 disposed on the top of the flexible tip portion 500. For example, ifthe bottom microelectrode 502 is in contact with tissue and the topmicroelectrode 502 is disposed in a blood pool, the bottom signal willbe different than the top signal. If both the bottom and topmicroelectrodes 502 are disposed in the blood pool, the bottom signaland the top signal can be the same in some embodiments. Thisdetermination can be made by an electronic control that is incommunication with each one of the microelectrodes, such as thatdiscussed in relation to FIG. 31.

As further depicted in FIG. 19D, the microelectrodes 502 can extendvertically from a surface of the understructure (e.g., first outboardarm 504). In some embodiments, microelectrodes 502 can have a thicknessin a range from 0.1 to 1000 microns. In some embodiments, themicroelectrodes 502 can have a thickness of 0.5 microns. By raising themicroelectrodes 502 off of a surface of the understructure, themicroelectrodes 502 can more easily contact tissue.

FIG. 20 depicts an isometric side, top, and distal end view of theflexible tip portion 500 depicted in FIG. 19A, according to variousembodiments of the present disclosure. The flexible tip portion 500includes those features as discussed in relation to FIGS. 19A to 19C. Inan example, the flexible tip portion 500 includes thelongitudinally-extending arms 504, 506, 508, 510, flared head portion512, head portion 514, and mounting portion 516. As depicted, thedifferent elements (e.g., longitudinally-extending arms 504, 506, 508,510, flared head portion 512, head portion 514, and mounting portion516) that form the flexible tip portion 500 can include planarcross-sections. For example, a thickness of each element can be lessthan a lateral width of each element. Accordingly, a top surface of theflexible tip portion 500 and a bottom surface of the flexible tipportion 500 can be flat, which can prove to be beneficial when formingthe microelectrodes 502, the electrically conductive traces 518, and/orthe contact pads 520 on the flexible tip portion 500. As discussedherein, an understructure of the flexible tip portion 500 can be formedfrom a flexible metal, such as nitinol, and/or a flexible printedcircuit board, upon which the microelectrodes 502, the electricallyconductive traces 518, and/or the contact pads 520 can be disposed.

FIG. 21 depicts a top view of an understructure of a flexible tipportion 540 of a high density electrode mapping catheter, according tovarious embodiments of the present disclosure. In some embodiments, theflexible tip portion 540 can include four microelectrode-carrier armsthat comprise a first outboard arm 542, a second outboard arm 548, afirst inboard arm 544, and a second inboard arm 546. These arms can belaterally separated from each other. The inboard portion of the flexibletip 540 can include a flared head portion 550 and the outboard portionof the flexible tip 540 can include a head portion 552, which areconnected via a connective portion 554. In some embodiments, the flaredhead portion 550 can include a lateral apex portion 556. In someembodiments, a lateral width L₁ of the lateral apex portion 556 can bein a range from 0.08 to 0.32 millimeters. In an example, the lateralwidth L₁ of the apex portion 556 can be approximately 0.16 millimeters.The flared head portion 550 can additionally include a tapered head arm558 that can have a width L₂ in a range from 0.10 to 0.45 millimeters.In an example, the width L₂ of the tapered head arm 558 can beapproximately 0.21 millimeters. In some embodiments, the arms that formthe head portion 552 can have a width L₃ in a range from −0.1 to 0.45millimeters. In an example, the width L₃ of the arms that form the headportion 552 can have a width of approximately 0.21 millimeters. Theconnective portion 554 can have a lateral width L₄ in a range from 0.08to 0.32 millimeters. In some embodiments, the connective portion 554 canhave a lateral width L₄ of approximately 0.16 millimeters.

The first outboard arm 542 and the second outboard arm 548 can includean outboard understructure and the first inboard arm 544 and the secondinboard arm 546 can include an inboard understructure, as previouslydiscussed. In some embodiments, a lateral width L₅ of the first andsecond inboard arms 544, 546 can be in a range from 0.10 to 1.0millimeters. In some embodiments, the lateral width L₅ of the first andsecond inboard arms 544, 546 can be approximately 0.51 millimeters. Insome embodiments, a lateral width L₆ of the first and second outboardarms 542, 548 can be in a range from 0.10 to 1.0 millimeters. In someembodiments, the lateral width L₆ of the first and second outboard arms542, 548 can be approximately 0.51 millimeters.

In some embodiments, a first outboard transition arm 562 can connect thefirst outboard arm 542 to the mounting portion 560; a first inboardtransition arm 564 can connect the first inboard arm 544 to the mountingportion 560; a second inboard transition arm 566 can connect the secondinboard transition arm 546 to the mounting portion; and a secondoutboard transition arm 568 can connect the second outboard arm 548 tothe mounting arm 560. In some embodiments, the width L₇ of the first andsecond outboard transition arms 562, 568 can be in a range from 0.10 to1.0 millimeters. In some embodiments, the width L₇ of the first andsecond outboard transition arms 562, 568 can be approximately 0.51millimeters.

In some embodiments, the flexible tip portion 540 can include a mountingportion 560, as previously discussed. In some embodiments, alongitudinal length L₈ of the mounting portion 560 can be in a rangefrom 5 to 20 millimeters. In some embodiments, the longitudinal lengthL₈ of the mounting portion 560 can approximately 11.1 millimeters. Insome embodiments, a longitudinal length L₉ of the inboard and outboardtransition arms can be in a range from 3 to 20 millimeters. In someembodiments, the longitudinal length L₉ of the portion of the flexibletip that includes the transition arms can be 9.1 millimeters. In someembodiments, a longitudinal length L₁₀ of the inboard and outboard armscan be in a range from 8 to 50 millimeters. In some embodiments, thelongitudinal length L₁₀ of the inboard and outboard arms can be 13.9millimeters. In some embodiments, a longitudinal length L₁₁ of theflared head portion 550 and the head portion 552 can be in a range from3 to 20 millimeters. In some embodiments, the longitudinal length L₁₁ ofthe flared head portion 550 and the head portion 552 can be 9.8millimeters.

In some embodiments, a lateral spacing L₁₂ between the first inboard arm544 and the second inboard arm 546 can be in a range from 0.10 to 4millimeters. In some embodiments, the lateral spacing L₁₂ between thefirst inboard arm 544 and the second inboard arm 546 can beapproximately 4 millimeters. In some embodiments, a lateral spacing L₁₃between the first inboard arm 544 and the first outboard arm 542 andbetween the second inboard arm 546 and the second outboard arm 548 canbe in a range from 0.10 to 4 millimeters. In some embodiments, thelateral spacing L₁₃ between can be approximately 4 millimeters.

FIG. 22 depicts a top view of an alternate embodiment of anunderstructure of a flexible tip portion 580 of a high density electrodemapping catheter, according to various embodiments of the presentdisclosure. In some embodiments, the flexible tip portion 580 caninclude four microelectrode-carrier arms that comprise a first outboardarm 582, a second outboard arm 588, a first inboard arm 584, and asecond inboard arm 586, which can be mounted to a mounting portion 596.The mounting portion 596, the inboard and outboard arms 582, 584, 586,588, the flared head portion 590, and head portion 592 can be formedfrom a single piece of material. The inboard portion of the flexible tip580 can include a flared head portion 590 and the outboard portion ofthe flexible tip 580 can include a head portion 592, which are connectedvia a connective portion 594. In some embodiments, the flared headportion 590 and the head portion 592 can have a greater longitudinallength that those depicted in FIG. 21. In some embodiments, the elementsthat form the flared head portion 590 and the head portion 592 can havea width that is less than that depicted in relation to FIG. 21. In anexample, by decreasing a width of the flared head portion 590 or thehead portion 592, or other parts of the flexible tip 580, a force whichis required to deflect the flared head portion 590, head portion 592 orother parts of the flexible tip 580 can be decreased. Accordingly, thevarious portions of the flexible tip 580 can be made more atraumatic.For example, the portions of the flexible tip 580 can more readilydeflect when they contact tissue as a result of the reduced deflectionforce.

FIGS. 23A-23F depict an isometric top and side view of an arm of anunderstructure of a high density electrode mapping catheter andassociated processing steps, according to various embodiments of thepresent disclosure. As depicted in FIG. 23A, the understructure 610 canbe formed from a flexible material in some embodiments. In an example,the flexible material can include nitinol and can be approximately 160microns thick, however the flexible material can be greater or less than160 microns thick. In some embodiments, the understructure 610 can becoated with a top dielectric layer 612-1 and/or bottom dielectric layer612-2, as depicted in FIG. 23B. In an example, the dielectric materialcan include, for example, a parylene, a polyimide, an epoxy, etc., aspreviously discussed herein. However, the dielectric material caninclude other types of dielectrics. In some embodiments, the dielectriclayer 612-1, 612-2 can be in a range from 1.0 to 30 microns thick. In anexample, the dielectric layer 612-1, 612-2 can be approximately 10microns thick, however, the dielectric material can be greater than orless than 10 microns thick. In some embodiments, the dielectric materialcan electrically insulate the understructure from conductive traces thatare formed on top of the dielectric layers. In some embodiments, a tielayer can be disposed between the dielectric material and the flexiblematerial. In an example, the tie layer can be sputtered chrome with athickness of approximately 1000 angstroms, although the thickness of thesputtered chrome can be greater than or less than 1000 angstroms thick.

In some embodiments, the dielectric layers 612-1, 612-2 can extendlaterally outward with respect to the understructure 610 to form anatraumatic inboard and/or outboard edge. In an example, theunderstructure 610 can have a planar cross-section, as previouslydiscussed herein, having a thickness that is less than a width of theunderstructure 610. In some embodiments, a lateral edge of theunderstructure 610 can be sharp, due to a relatively thin thickness ofthe understructure 610. To provide an atraumatic lateral edge (e.g.,outboard and/or inboard edge) of the understructure 610, the dielectriclayers 612-1, 612-2 can extend laterally outward with respect to theunderstructure 610, as depicted in FIG. 23C. The atraumatic edge can actas a protector/bumper to prevent the understructure 610 from contactingother materials (e.g., inner diameter of an introducer sheath, tissuesin the heart, etc.).

FIG. 23C is a cross-sectional view of the coated understructure 610depicted in FIG. 23B, along the line 23C-23C. For example, the first andsecond dielectric layers 612-1, 612-2 can include a first and secondoutboard overhang 614-1, 614-2 and the first and second dielectriclayers 612-1, 612-2 can include a first and second inboard overhang616-1, 616-2, as depicted in FIG. 23C. In some embodiments, the firstand second outboard overhang 614-1, 614-2 and/or the first and secondinboard overhang 616-1, 616-2 can be formed on each portion of aflexible tip portion of a high density electrode mapping catheter, suchas that discussed in relation to FIGS. 19A to 22. For example, withrespect to the flexible tip portion 540 depicted and discussed inrelation to FIG. 21, an outboard understructure 622 that includes thefirst outboard transition arm 562, the first outboard arm 542, the headportion 552, the second outboard arm 548, and the second outboardtransition arm 568 can have a first and second outboard overhang 614-1,614-2 disposed along an outboard edge 618 that extends along a perimeterof the outboard understructure 622 (FIG. 21). In some embodiments, thefirst and second outboard overhang 614-1, 614-2 can be disposed alongthe outboard edge 618 of one or more of the first outboard transitionarm 562, the first outboard arm 542, the head portion 552, the secondoutboard arm 548, and/or the second outboard transition arm 568. In someembodiments, the outboard understructure 622 can have a first and secondinboard overhang 616-1, 616-2 disposed along an inboard edge 620 of theoutboard understructure 622. In some embodiments, the first and secondinboard overhang 616-1, 616-2 can be disposed along the inboard edge 620of one or more of the first outboard transition arm 562, the firstoutboard arm 542, the head portion 552, the second outboard arm 548,and/or the second outboard transition arm 568.

With further reference to FIG. 21, in some embodiments, an inboardunderstructure 624 that includes the first inboard transition arm 564,the first inboard arm 544, the flared head portion 550, the secondinboard arm 546, and the second inboard transition arm 566 can have afirst and second outboard overhang 614-1, 614-2 disposed along anoutboard edge 626 that extends along a perimeter of the inboardunderstructure 624 (FIG. 21). In some embodiments, the first and secondoutboard overhang 614-1, 614-2 can be disposed along the outboard edge624 of one or more of the first inboard transition arm 564, the firstinboard arm 626, the flared head portion 550, the second inboard arm546, and/or the second inboard transition arm 566. In some embodiments,the inboard understructure 624 can have a first and second inboardoverhang 616-1, 616-2 disposed along an inboard edge 628 of the inboardunderstructure 624. In some embodiments, the first and second inboardoverhang 616-1, 616-2 can be disposed along the inboard edge 628 of oneor more of the first inboard transition arm 564, the first inboard arm544, the flared head portion 550, the second inboard arm 546, and/or thesecond inboard transition arm 566.

As depicted in FIG. 23D, one or more electrically conductive traces636-1, 636-2 and/or electrically conductive pads 638 can be formed on anouter surface of the dielectric material 612-1, 612-2. In someembodiments, one or more electrically conductive traces 636-1, 636-2and/or electrically conductive pads 638 can be formed on the outersurface of the first dielectric layer 612-1 and/or the outer surface ofthe second dielectric layer 612-2. In some embodiments, the electricallyconductive traces 636-1, 636-2 and/or the electrically conductive pads638 can be formed from an electrically conductive material, such ascopper. The copper can have a thickness of approximately 7 microns,although the thickness of the copper can be greater or less than 7microns. In some embodiments, a tie layer can be included between theelectrically conductive traces 636-1, 636-2 and the dielectric material612-1, 612-2. In an example, the tie layer can be sputtered chrome witha thickness of approximately 130 angstroms. However, the thickness ofthe tie layer can be greater than or less than 130 angstroms.

As depicted in FIG. 23E, the first dielectric layer 612-1 has beencoated with a first overcoat dielectric layer 640-1 and the seconddielectric layer 612-2 has been coated with a second overcoat dielectriclayer 640-2. In some embodiments, the overcoat dielectric layers 640-1,640-2 can protect the one or more electrically conductive traces 636-1,636-2 and/or the one or more electrically conductive pads 638 and/orprevent the one or more electrically conductive traces 636-1, 636-2and/or the one or more electrically conductive pads 638 from contactingtissue. In some embodiments, an exposed area 642 can be created in theovercoat dielectric layer 640-1 and the overcoat dielectric layer 640-2(although not shown). In an example, the exposed area 642 can be a viathat extends through the overcoat dielectric layer 640-1, such that theelectrically conductive pad 638 can be accessed. In some embodiments,the overcoat dielectric layers 640-1, 640-2 can have a thickness ofapproximately 10 microns, although the thickness of the overcoat layerscan be greater than or less than 10 microns. As depicted in FIG. 23F, anelectrode 644 can be disposed on an outer surface of the overcoatdielectric layer 640-1. In an example, the electrode 644 can be formedfrom an electrically conductive material, such as gold. The gold can beapproximately 0.5 microns thick, although the thickness of the gold canbe greater than or less than 0.5 microns thick. In some embodiments, atie layer can be disposed between the conductive pad 638 and theelectrode 644. In an example, the tie layer can include nickel. In someembodiments, the nickel can have a thickness of approximately 0.4microns, although the thickness of the nickel can be greater than orless than 0.4 microns.

FIG. 24A depicts a top view of an understructure of a flexible tipportion 660 of a high density electrode mapping catheter that includes aplurality of electrodes 662-1, 662-2, 662-3, 662-4, hereinafter referredto in the plural as electrodes 662, traces 664, and a mounting portion666, according to various embodiments of the present disclosure. Asdiscussed herein, the flexible tip portion 660 can include a firstoutboard arm 668, a first inboard arm 670, a second inboard arm 672, anda second outboard arm 674. In some embodiments, the flexible tip portion660 can include a first outboard transition arm 676, a first inboardtransition arm 678, a second inboard transition arm 680, and a secondoutboard transition arm 682. A proximal end of the transition arms canbe connected to the mounting portion, which includes a contact pad 684.As discussed in relation to FIGS. 8A to 8C, electrically conductivetraces 664 can be connected to each one of the electrodes disposed onthe understructure of the flexible tip portion 660. The electricallyconductive traces 664 can extend proximally from each one of theelectrodes 662 down each of the outboard arms 668, 674, inboard arms670, 672, outboard transition arms 676, 682, and inboard transition arms678, 680, to the mounting portion 666. In some embodiments, theelectrically conductive traces 664 can terminate at a first or secondrow of contact pads 684-1, 684-2, as previously discussed in relation toFIG. 19A. In some embodiments, test traces can extend proximally fromeach one of the contact pads in the first and second row of contact pads684-1, 684-2. As generally depicted in FIG. 24A, a density ofelectrically conductive traces 664 covering the understructure of theflexible tip portion 660 increases in the proximal direction. Forexample, as depicted, a proximal portion of the outboard mounting arms668, 674 and inboard mounting arms 678, 680; each one of the outboardtransition arms 676, 682 and the inboard transition arms 678, 680; andthe mounting portion 666 can include electrically conductive traces 664that cover a majority of their surfaces, as depicted.

As depicted in FIG. 24B, the junction between the proximal end of thesecond outboard arm 674 and the second outboard transition arm 682 caninclude a plurality of electrically conductive traces 664 that cover amajority of the second outboard arm 674 and the second outboardtransition arm 682. In some embodiments, the traces can extend beneatheach one of the plurality of electrodes 662, as previously discussedherein, for example, in relation to FIG. 4D. In some embodiments, vias688-1, 688-2, 688-3, 688-4, hereinafter referred to in the plural asvias 688, can be formed in a dielectric coating that covers theunderstructure of the flexible tip portion 660 and can provide anelectrical connection between each one of the electrically conductivetraces 664 and each one of the electrodes 662. In some embodiments, eachone of the electrically conductive traces 664 can be routed around eachone of the vias 688. In an example, each one of the electricallyconductive traces 664 can have a routing bend 690-1, 690-2, 690-3,690-4, 690-4, 690-5, hereinafter referred to in the plural as routingbends 690, in a portion of the electrically conductive trace 664 that isadjacent to each one of the vias 688. In an example, the routing bends690 can be formed towards a proximal end of the outboard and inboardarms, where a density of the electrically conductive traces 664 isincreased. For instance, in order to route the electrically conductivetraces 664 around the vias 688, the traces 664 can be routed outward orinwardly with respect to a longitudinal axis of the flexible tip portion660 around the vias 688. As depicted in FIG. 24B, routing bends 690-1,690-2, 690-3 can be included in the trace 664. The routing bends 690-1,690-2, 690-3 can become larger (e.g., extend further outward or inward),in some embodiments, as the trace 664 extends proximally along theunderstructure (e.g., second outboard arm 674).

FIG. 24C depicts an enlarged top view of a portion 696 of the flexibletip portion 660 that includes first and second rows of contact pads684-1, 684-2 depicted in FIG. 24A, according to various embodiments ofthe present disclosure. As depicted, the plurality of traces 664 canextend along the outboard and inboard transition arms 676, 682, 678, 680and the mounting portion 666 to contact pads (e.g., contact pad 692). Insome embodiments, the mounting portion 666 can include flared contactpad portions 694-1, 694-2. In an example, the flared contact padportions 694-1, 694-2 can extend laterally from either side of themounting portion 666 and can provide an area that includes an increasedlateral width, which can provide increased space for mounting the firstand second rows of contact pads 684-1, 684-2.

FIG. 25A depicts a top view of an understructure of a flexible tipportion 700 of a high density electrode mapping catheter that includes aplurality of electrodes 702-1, 702-2, 702-3, 702-4 and rows of contactpads 704-1, 704-2, 704-3, 704-4, according to various embodiments of thepresent disclosure. The flexible tip portion 700 can include a firstoutboard arm 706, second outboard arm 712, first inboard arm 708, and asecond inboard arm 710. In some embodiments, the flexible tip portion700 can include a mounting portion 714 that is connected to the outboardarms 706, 712 via a first outboard transition arm 716 and secondoutboard transition arm 722. The mounting portion 714 can be connectedto the first and second inboard arms 708, 710 via a first inboardtransition arm 718 and a second inboard transition arm 720.

As depicted in FIG. 25A, a plurality of electrodes (e.g., electrodes702-1, 702-2, 702-3, 702-4) can be disposed along the arms of theflexible tip portion 700. FIG. 25B depicts an enlarged view of a portion724 of the flexible tip portion 700 depicted in FIG. 25A, according tovarious embodiments of the present disclosure. In some embodiments,portions of the understructure that form the outboard arms 706, 712and/or the inboard arms 708, 710 can include bumpouts 726-1, 726-1,726-3, 726-4, 726-5, hereinafter referred to in the plural as bumpouts726. In some embodiments, the bumpouts 726 can laterally extend fromareas of the understructure that include the electrodes 702. Aspreviously discussed in relation to FIG. 24B, traces that proximallyextend from each of the electrodes 702 can have routing bends 690 (FIG.24B). In some embodiments, the routing bends 690 can be disposed on thebumpouts 726.

FIG. 25C depicts an enlarged top view of the mounting portion 714 of theflexible tip portion depicted in FIG. 25A, according to variousembodiments of the present disclosure. As depicted, the mounting portion714 can include flared contact pad portions 730-1, 730-2. In someembodiments, the flared contact pad portions 730-1, 730-2 can increase alateral width of the mounting portion 714, such that rows of contactpads 704-1, 704-2, 704-3, 704-4 can be disposed on the mounting portion714, as previously discussed herein. In some embodiments, each row ofcontact pads 704 can include a plurality of laterally spaced apartcontact pads 732-1, 732-2, . . . , 732-8. In some embodiments, each rowof contact pads 704 can include a common ground 734. In someembodiments, each row of contact pads 704 can correspond to the set ofelectrodes 702 disposed on the outboard and inboard arms. In an example,a first row of contact pads 704-1 can correspond to microelectrodesdisposed on the first outboard arm 706; the second row of contact pads704-2 can correspond to microelectrodes disposed on the first inboardarm 708; the third row of contact pads 704-3 can correspond tomicroelectrodes disposed on the second inboard arm 710; and the fourthrow of contact pads 704-4 can correspond to microelectrodes disposed onthe second outboard arm 712. In some embodiments, as depicted, each rowof contact pads 704 can include a ground pad 734, which can serve as aground for electrodes disposed on a corresponding arm of the flexibletip portion 700. In some embodiments, each row of contact pads 704 canbe longitudinally spaced apart from one another, as depicted. Althoughnot depicted, an opposite side of the mounting portion 714 can includeadditional rows of contact pads. For example, where electrodes aredisposed on both sides of the outboard understructure and the inboardunderstructure, contact pads can be disposed on either side of themounting portion 714. Contact pads disposed on a first side of themounting portion 714 can be electrically coupled to electrodes disposedon a first side of the outboard and inboard understructure, whilecontact pads disposed on a second side of the mounting portion 714 canbe electrically coupled to electrodes disposed on a second side of theoutboard and inboard understructure.

FIG. 26 depicts a flexible tip portion 740 of a high density electrodemapping catheter similar to that depicted in FIG. 19A that includes aplurality of wires 746 connected to contact pads disposed on a mountingportion 742, according to various embodiments of the present disclosure.In an example, as discussed herein, the flexible tip portion can includea mounting portion 742 upon which a plurality of contact pads aredisposed (hidden from view in FIG. 26). In some embodiments, a wire(e.g., wire 746) can be connected to each one of the contact pads,electrically coupling each electrode (e.g., electrode 748) disposed onthe flexible tip portion 740 and an associated electrically conductivetrace 750 with the wire 746.

FIG. 27A depicts sections of flex cable 752, according to variousembodiments of the present disclosure. In some embodiments, a firstsection of flex cable 754-1, a second section of flex cable 754-2, and athird section of flex cable 754-3, hereinafter referred to in the pluralas flex cable 754 are depicted. In an example, each section of flexcable includes a plurality of electrically conductive traces. Forexample, the first section of flex cable 754-1 can include theelectrically conductive traces 758-1, 758-2, . . . , 758-8, hereinafterreferred to in the plural as electrically conductive traces 758. In someembodiments, the plurality of electrically conductive traces 758 can bedisposed on a polymer backing 766, as further discussed in relation toFIG. 27B. Additionally, each one of the sections of flex cable caninclude a ground trace 764 that extends parallel with the electricallyconductive traces 758. In some embodiments, test sections 756-1, 756-2can be disposed between the sections of flex cable 754. In an example,each test section 756-1, 756-2 can include a plurality of test traces762-1, 762-2, . . . , 762-8, hereinafter referred to in the plural astest traces 762, that are connected to each one of the electricallyconductive traces 758. In some embodiments, each test section 756-1,756-2 can also include a ground test trace 764 that is electricallyconnected to the ground trace 764. In some embodiments, the test traces762 and the ground test trace 764 can have a wider lateral width thanthe electrically conductive traces 758 to allow for an instrument toprobe the traces of the test section 756. The ground test trace 764 caninclude a via 768 that extends through the polymer backing 766 andelectrically couples the ground test trace 764 to a grounding pad 772(FIG. 27B).

In some embodiments, the ground test trace 764 can include a via thatelectrically connects it to a grounding pad 772, as further depicted inFIG. 27B. FIG. 27B depicts a cross-sectional end view of a ground trace760 of the flex cable 752 depicted in FIG. 27A, according to variousembodiments of the present disclosure. In some embodiments, the groundtrace 760 can be formed from copper and can be disposed on top of apolymer backing 766. The ground trace 760 can have a thickness ofapproximately 10 micrometers, although the thickness of the ground trace760 can be greater than or less than 10 micrometers. In an example, thepolymer backing 766 can be formed from a polyimide. The polymer backing766 can have a thickness of approximately 25 micrometers, although thethickness of the polymer backing 766 can be greater than or less than 25micrometers. In some embodiments, each flex cable can have a groundtrace 760, providing signal noise reduction and improvingelectrocardiogram signals that are received by the microelectrodes andpassed through the flex cable 752.

In some embodiments, a grounding pad 772 can be disposed on an oppositeside of the polymer backing 766 from the ground trace 760. The groundingpad 772 can have a thickness of approximately 12 micrometers, althoughthe thickness of the grounding pad 772 can be greater than or less than12 micrometers. In some embodiments, as discussed in relation to FIG.27A, a via (not depicted) can be formed in the polymer backing 766 andcan electrically couple the ground trace 760 to the grounding pad 772.In some embodiments, a first layer of polymer 770 can be disposed on atop of the flex circuit and a second layer of polymer 774 can bedisposed on a bottom of the flex circuit to protect the traces (e.g.,ground trace 760) and/or the grounding pad 772. The first layer ofpolymer 770 can have a thickness of approximately 15 micrometers,although the thickness of the first layer of polymer 770 can be greaterthan or less than 15 micrometers. The second layer of polymer 774 canhave a thickness of approximately 25 micrometers, although the thicknessof the second layer of polymer 774 can be greater than or less than 15micrometers. In some embodiments, the first and second layer of polymercan include a polymer, such as a polymer selected from a DissipationFactor-Photo Sensitive Resist (DF-PSR) group of materials.

In some embodiments, one or more flex cables 752 can be electricallycoupled with microelectrodes disposed on a flexible tip portion of ahigh density electrode mapping catheter, as discussed herein. Asdepicted, the flex cable 752 can include eight test traces 762 and acommon ground. In some embodiments, five flex cables can be attached toeach side of the flexible tip portion of the high density electrodemapping catheter to allow for forty microelectrodes per side of theflexible tip portion. This can save time and resources as a result ofproviding a semi-automated process versus the individual soldering offorty contacts per side. In an example, each flex cable 752 can have amating pattern on a contact pad disposed on the flexible tip portion.For example, the flex cable 752 can be mated with a row of contact pads704 (FIG. 25C).

FIG. 28 depicts a flexible tip portion 780 of a high density electrodemapping catheter disposed in a distal end of a catheter shaft 782,according to various embodiments of the present disclosure. The flexibletip portion 780 of the high density electrode mapping catheter caninclude those features as discussed herein. As depicted, a proximalportion of the flexible tip portion 780 is disposed in the distal end ofthe catheter shaft 782. Although not depicted, a mounting portion of theflexible tip portion 780, as discussed herein, can be disposed in alumen defined by the distal end of the catheter shaft 782. In someembodiments, a connector 784 can be disposed at the distal end of thecatheter shaft 782 and can connect the flexible tip portion 780 to thedistal end of the catheter shaft 782. As depicted, a first outboardtransition arm 786, a second outboard transition arm 792, a firstinboard transition arm 788, and a second inboard transition arm 790 canextend distally from the connector 784 and the distal end of thecatheter shaft 782. In some embodiments, and as depicted, an adhesive794 (e.g., epoxy) can be disposed around the proximal end of thetransitional arms and the connector 784 to secure the flexible tipportion 780 with the catheter shaft 782.

FIG. 29 depicts a high density electrode mapping catheter 800, accordingto various embodiments of the present disclosure. In some embodiments,the high density electrode mapping catheter 800 can include a flexibletip portion 802 disposed at a distal end of a catheter shaft 804. Insome embodiments, the catheter shaft 804 can include one or more ringelectrodes 806-1, 806-2, as discussed herein. In some embodiments, theflexible tip portion 802 can include electrodes disposed on both sidesof the flexible tip portion 802. In some embodiments, a cable to shaftcoupler can be disposed at a proximal end of the catheter shaft 804 andcan couple a first sensing cable 808-1 and a second sensing cable 808-2with the catheter shaft. In some embodiments, the first sensing cable808-1 can include electrical connections for electrodes disposed on afirst side of the flexible tip portion 802 and the second sensing cable808-2 can include electrical connections for electrodes disposed on asecond side of the flexible tip portion 802. In some embodiments, thefirst sensing cable 808-1 can include electrical connections for theelectrodes disposed on the flexible tip portion 802 and the secondsensing cable 808-2 can include electrical connections for the ringelectrodes 806-1, 806-2. In some embodiments, a proximal end of thefirst and second sensing cables 808-1, 808-2 can include a first andsecond connector 810-1, 810-2, which can be connected to a computerconfigured to analyze signals received from the electrodes disposed onthe flexible tip portion 802.

FIG. 30 depicts another embodiment of a high density electrode mappingcatheter 820, according to various embodiments of the presentdisclosure. In some embodiments, the high density electrode mappingcatheter 820 can include a flexible tip portion 822 disposed at a distalend of a catheter shaft 824. In contrast to FIG. 29, the catheter shaft824 does not include ring electrodes. In some embodiments, the flexibletip portion 822 can include electrodes disposed on both sides of theflexible tip portion 822. In some embodiments, a cable to shaft coupler826 can be disposed at a proximal end of the catheter shaft 824 and cancouple a first sensing cable 828-1 and a second sensing cable 828-2 withthe catheter shaft 824. In some embodiments, the first sensing cable828-1 can include electrical connections for electrodes disposed on afirst side of the flexible tip portion 822 and the second sensing cable828-2 can include electrical connections for electrodes disposed on asecond side of the flexible tip portion 822. In some embodiments, aproximal end of the first and second sensing cables 828-1, 828-2 caninclude a first and second connector 820-1, 820-2, which can beconnected to a computer configured to analyze signals received from theelectrodes disposed on the flexible tip portion 822.

FIG. 31 depicts a schematic and block diagram view of a medical system840, in accordance with embodiments of the present disclosure. System840, as depicted, includes a main electronic control unit 842 (e.g., aprocessor) having various input/output mechanisms 844, a display 846, anoptional image database 848, an electrocardiogram (ECG) monitor 850, alocalization system, such as a medical positioning system 852, a medicalpositioning system-enabled elongate medical device 854, a patientreference sensor 856, a magnetic position sensor 858, an electrode 860(e.g., position sensing electrode), and a microelectrode 862 configuredto sense electrical signals produced by the heart. For simplicity, onemagnetic position sensor 858, one electrode 860, and one microelectrode862 are shown, however, more than one magnetic position sensor 858, morethan one electrode 860, and/or more than one microelectrode 862 can beincluded in the system 300.

Input/output mechanisms 844 may comprise conventional apparatus forinterfacing with a computer-based control unit including, for example,one or more of a keyboard, a mouse, a tablet, a foot pedal, a switchand/or the like. Display 846 may also comprise conventional apparatus,such as a computer monitor.

System 840 may optionally include image database 848 to store imageinformation relating to the patient's body. Image information mayinclude, for example, a region of interest surrounding a destinationsite for medical device 854 and/or multiple regions of interest along anavigation path contemplated to be traversed by medical device 854. Thedata in image database 848 may comprise known image types including (1)one or more two-dimensional still images acquired at respective,individual times in the past; (2) a plurality of related two-dimensionalimages obtained in real-time from an image acquisition device (e.g.,fluoroscopic images from an x-ray imaging apparatus), wherein the imagedatabase acts as a buffer (live fluoroscopy); and/or (3) a sequence ofrelated two-dimensional images defining a cine-loop wherein each imagein the sequence has at least an ECG timing parameter associatedtherewith, adequate to allow playback of the sequence in accordance withacquired real-time ECG signals obtained from ECG monitor 314. It shouldbe understood that the foregoing embodiments are examples only and notlimiting in nature. For example, the image database may also includethree-dimensional image data as well. It should be further understoodthat the images may be acquired through any imaging modality, now knownor hereafter developed, for example X-ray, ultra-sound, computerizedtomography, nuclear magnetic resonance or the like.

ECG monitor 850 is configured to continuously detect an electricaltiming signal of the heart organ through the use of a plurality ofmicroelectrodes 862. The timing signal generally corresponds to aparticular phase of the cardiac cycle, among other things. Generally,the ECG signal(s) may be used by the control unit 842 for ECGsynchronized play-back of a previously captured sequence of images (cineloop) stored in database 848. ECG monitor 850 and ECG-electrodes mayboth comprise conventional components. In some embodiments, the maincontrol 842 can include a computing device, which can include hardwareand/or a combination of hardware and programming that is configured todetermine a difference in signals received by microelectrodes, asdiscussed in relation to FIG. 19D. For example, the main control 842 caninclude a non-transitory computer readable medium that storesinstructions, which are executable by a processor, in communication withthe main control 842, to determine a difference in signals received frommicroelectrodes. Medical positioning system 852 is configured to serveas the localization system and therefore to determine position(localization) data with respect to one or more magnetic positionsensors 858 and/or electrodes 860 and output a respective locationreading.

FIG. 32 depicts a method 870 control block flow diagram for determininga degree of contact between a first electrode and tissue, according tovarious embodiments of the present disclosure. In some embodiments, aspreviously discussed herein, for example in relation to FIG. 19D, themethod 870 can include receiving a first electrical signal from thefirst electrode disposed on a first side of a tip portion of a medicaldevice, at method control block 872. The method 870 can further includereceiving a second electrical signal from a second electrode disposed ona second side of the tip portion of the medical device, at methodcontrol block 874. As previously discussed, the first electrode and thesecond electrode can be disposed vertically adjacent with respect to oneanother. For example, the first electrode can be disposed directlybeneath the second electrode, as depicted and discussed in relation toFIG. 19D.

In some embodiments, the method 870 can include determining the degreeof contact between the first electrode and the tissue based on acomparison between the first electrical signal and the second electricalsignal, at method control block 876. In an example, when the firstelectrode is disposed against tissue, the second electrode can bedisposed on the opposite side of the medical device and in a blood pool.As such, a different electrical signal (e.g., voltage) can be receivedfrom the first electrode versus the second electrode. Accordingly, insome embodiments, the comparison between the first electrical signal andthe second electrical signal can include comparing a first voltageassociated with the first electrical signal and a second voltageassociated with the second electrical signal.

In an example, cardiac tissue can generate a voltage whenever itdepolarizes. The voltage can propagate through the heart muscle and alsothrough the blood pool and can be picked up by both the first electrodeand the second electrode. If one of the electrodes (e.g., firstelectrode) is touching the tissue, then that voltage will be differentthan the voltage picked up by the electrode disposed in the blood pool(e.g., second electrode). The difference between the first electricalsignal associated with the first electrode and the second electricalsignal associated with the second electrode will be greater when thefirst electrode is touching the tissue and the second electrode isdisposed in the blood pool. The difference between the first electricalsignal associated with the first electrode and the second electricalsignal associated with the second electrode will be smaller when thefirst electrode and second electrode are both disposed in the bloodpool.

Based on the differences in electrical signals (e.g., voltages), adetermination of contact between the medical device (e.g., firstelectrode) and the tissue can be made. For example, the method 870 caninclude determining that the first electrode is not in contact with thetissue when the first voltage associated with the first electricalsignal and the second voltage associated with the second electricalsignal are the same. For example, when the voltages associated with thefirst electrode and the second electrode are the same, this can be anindication that the first electrode and the second electrode aredisposed in the blood pool and are not in contact with the tissue. Insome embodiments, the method can include determining that the firstelectrode is not in contact with the tissue when a difference betweenthe first voltage associated with the first electrical signal and thesecond voltage associated with the second electrical signal is less thana threshold voltage (e.g., the voltages are close to being the same).For example, the voltages associated with each of the first and secondelectrodes may not be exactly the same due to electrical interference inthe blood pool.

Alternatively, in some embodiments, the method 879 can includedetermining that the first electrode is in contact with the tissue whenthe first voltage associated with the first electrical signal isdifferent than the second voltage associated with the with the secondelectrical signal. In an example, the method 879 can include determiningthat the first electrode is in contact with the tissue when a differencebetween the first voltage associated with the first electrical signaland the second voltage associated with the second electrical signal isgreater than a threshold value. For instance, the method 879 can includedetermining that the first electrode is in contact with the tissue whenthe first voltage associated with the first electrical signal is greaterthan the second voltage associated with the second electrical signal(e.g., is greater than a defined threshold value). As discussed, whenthe first electrode is disposed against the tissue and the secondelectrode is disposed in the blood pool, the first electrical signalassociated with the first electrode can have a greater voltage than thesecond electrical signal.

In some embodiments, the method 870 can include determining that adegree of contact between the first electrode and the tissue isincreasing based on the first voltage associated with the firstelectrical signal being increased with respect to the second voltageassociated with the second electrical signal. For example, if the firstvoltage associated with the first electrical signal increases at agreater rate than the second voltage associated with the secondelectrical signal and/or increases while the second voltage stays thesame, a determination can be made that a degree of contact between thefirst electrode and the tissue is increasing. In some embodiments,ensuring that sufficient contact exists between the medical device andthe tissue can be beneficial where diagnostic information is beingcollected by the medical device (e.g., electrodes) and/or therapeuticenergy is being delivered to the tissue from the medical device (e.g.,electrodes). Alternatively, the method 870 can include determining thata degree of contact between the first electrode and the tissue isdecreasing based on the first voltage associated with the firstelectrical signal being decreased with respect to the second voltageassociated with the second electrical signal.

In some embodiments, the first and/or second electrode can be configuredto be driven by an electrical current (e.g., high frequency electricalcurrent). In an example, the first and/or second electrode can be drivenwith the electrical current and a voltage (e.g., high frequency voltage)can be induced by the electrical current. For instance, a voltage can beinduced in the cardiac tissue and/or in the blood pool. Accordingly, aninduced voltage, which is generated by one or more of the electrodes,rather than the heart, can be received by one or more of the electrodeson the medical device. The induced voltage (e.g., impedance) associatedwith an electrical signal received from one of the electrodes can bemeasured. Depending on whether an electrode from which the electricalsignal is received is disposed in the blood pool or is in contact withthe tissue, the electrical signal can vary. In an example, the inducedvoltages that are measured from an electrical signal received from thefirst electrode and the second electrode can be different if one of theelectrodes is disposed against tissue and one of the electrodes isdisposed in the blood pool and can be similar if both electrodes aredisposed in the blood pool.

In some embodiments, one or both of the first electrode and the secondelectrodes can be driven with the current and one or more otherelectrodes disposed on the medical device or an electrode disposed on askin patch can receive an induced voltage. In some embodiments, thecurrent can be induced in the first electrode and an induced voltage canbe received by the second electrode. Depending on whether the secondelectrode is disposed in the blood pool or in contact with cardiactissue can affect a magnitude of the induced voltage. Likewise, thecurrent can be induced in the second electrode and an induced voltagecan be received by the first electrode. Depending on whether the firstelectrode is disposed in the blood pool or in contact with cardiactissue can affect a magnitude of the induced voltage. In someembodiments, a current can be induced in another electrode disposed onthe medical device and an induced voltage can be received by one or bothof the first and second electrodes. Induced voltages associated withelectrical signals received from the first and second electrodes canvary depending on whether one or more of the first and second electrodesare disposed in the blood pool or disposed against cardiac tissue, asdiscussed herein.

FIG. 33 depicts a method 880 control block flow diagram for determininga cardiac activation associated with endocardial tissue, according tovarious embodiments of the present disclosure. As discussed in relationto FIG. 33, the method 880 can include receiving a first electricalsignal from a first electrode disposed on a first side of a tip portionof a medical device, at method control block 882. In some embodiments,the method 880 can include receiving a second electrical signal from asecond electrode disposed on a second side of the tip portion of themedical device, at method control block 884. As previously discussed,the first electrode and the second electrode can be disposed verticallyadjacent with respect to one another in a manner analogous to thatdepicted and discussed in relation to FIG. 19D.

In some embodiments, the method 880 can include determining acharacteristic associated with the cardiac activation, wherein thecardiac activation is in a direction that is normal to a surface of theendocardial tissue, at method control block 886. In an example, becausethe first electrode and the second electrode are vertically adjacent toone another, as a cardiac activation travels through endocardial tissue,an electrical activation signal can be received by the first electrodedisposed against the tissue and can then be received by the secondelectrode that is vertically adjacent to the first electrode. Forinstance, as the electrical activation signal travels toward a surfaceof the endocardial tissue on which the first electrode is disposed, theelectrical activation signal can travel in a direction that is normal tothe surface of the endocardial tissue, toward the first electrode. Asthe electrical activation signal reaches the surface of the endocardialtissue on which the first electrode is disposed, a first electricalsignal can be received from the first electrode. The electricalactivation signal can then travel through a portion of the blood pooland can be received by the second electrode disposed vertically adjacentto the first electrode. This can allow for a better measurement of theelectrical activation signal since the two electrodes are disposedvertically adjacent to one another.

In some embodiments, the characteristic associated with the cardiacactivation can include a direction of the cardiac activation. Forexample, a determination that a component of a directional vector of thecardiac activation is normal to a surface of the endocardial tissue canbe made. In some embodiments, it can be common for cardiac activation tobe in a direction that is normal to the surface of the endocardialtissue. For example, in thick ventricular tissue, cardiac activation canbe in a direction that is normal to the surface of the endocardialtissue.

In some embodiments, the method 880 can include filtering out noise fromthe first electrical signal based on the second electrical signal. Forexample, where the first electrode is disposed against the surface ofthe endocardial tissue, surrounding noise can have negative effects onthe first electrical signal associated with the first electrode. Thesurrounding noise can be caused by stray electrical signals that areflowing through the blood pool in some embodiments. Accordingly, thesecond electrode, which is disposed in the blood pool can receive anystray electrical signals that are flowing through the blood pool, whichcan be represented in the second electrical signal associated with thesecond electrode. In some embodiments, the second electrical signal canbe used to filter out the stray electrical signals from the firstelectrical signal.

In some embodiments, the method 870 and method 880 can be executed by acomputer such as that discussed in relation to FIG. 31. In someembodiments, the method control blocks (e.g., control blocks 872, 874,876, 882, 884, 886) can represent computer executable instructions thatcan be stored on a non-transitory computer readable medium (CRM), whichcan be executed by a processor in communication with the computer toperform a particular function (e.g., receive a first electrical signalfrom the first electrode disposed on a first side of a tip portion of amedical device).

Embodiments are described herein of various apparatuses, systems, and/ormethods. Numerous specific details are set forth to provide a thoroughunderstanding of the overall structure, function, manufacture, and useof the embodiments as described in the specification and illustrated inthe accompanying drawings. It will be understood by those skilled in theart, however, that the embodiments may be practiced without suchspecific details. In other instances, well-known operations, components,and elements have not been described in detail so as not to obscure theembodiments described in the specification. Those of ordinary skill inthe art will understand that the embodiments described and illustratedherein are non-limiting examples, and thus it may be appreciated thatthe specific structural and functional details disclosed herein may berepresentative and do not necessarily limit the scope of theembodiments, the scope of which is defined solely by the appendedclaims.

Reference throughout the specification to “various embodiments,” “someembodiments,” “one embodiment,” or “an embodiment”, or the like, meansthat a particular feature, structure, or characteristic described inconnection with the embodiment(s) is included in at least oneembodiment. Thus, appearances of the phrases “in various embodiments,”“in some embodiments,” “in one embodiment,” or “in an embodiment,” orthe like, in places throughout the specification, are not necessarilyall referring to the same embodiment. Furthermore, the particularfeatures, structures, or characteristics may be combined in any suitablemanner in one or more embodiments. Thus, the particular features,structures, or characteristics illustrated or described in connectionwith one embodiment may be combined, in whole or in part, with thefeatures, structures, or characteristics of one or more otherembodiments without limitation given that such combination is notillogical or non-functional.

It will be appreciated that the terms “proximal” and “distal” may beused throughout the specification with reference to a clinicianmanipulating one end of an instrument used to treat a patient. The term“proximal” refers to the portion of the instrument closest to theclinician and the term “distal” refers to the portion located furthestfrom the clinician. It will be further appreciated that for concisenessand clarity, spatial terms such as “vertical,” “horizontal,” “up,” and“down” may be used herein with respect to the illustrated embodiments.However, surgical instruments may be used in many orientations andpositions, and these terms are not intended to be limiting and absolute.

Although at least one embodiment for a high density electrode mappingcatheter has been described above with a certain degree ofparticularity, those skilled in the art could make numerous alterationsto the disclosed embodiments without departing from the spirit or scopeof this disclosure. All directional references (e.g., upper, lower,upward, downward, left, right, leftward, rightward, top, bottom, above,below, vertical, horizontal, clockwise, and counterclockwise) are onlyused for identification purposes to aid the reader's understanding ofthe present disclosure, and do not create limitations, particularly asto the position, orientation, or use of the devices. Joinder references(e.g., affixed, attached, coupled, connected, and the like) are to beconstrued broadly and may include intermediate members between aconnection of elements and relative movement between elements. As such,joinder references do not necessarily infer that two elements aredirectly connected and in fixed relationship to each other. It isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative only andnot limiting. Changes in detail or structure may be made withoutdeparting from the spirit of the disclosure as defined in the appendedclaims.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

1.-20. (canceled)
 21. An integrated electrode structure comprising: acatheter shaft comprising a proximal end and a distal end, the cathetershaft defining a catheter shaft longitudinal axis; a flexible tipportion located adjacent to the distal end of the catheter shaft andadapted to conform to a tissue, the flexible tip portion comprising aflexible framework formed from a planar substrate, the planar substratedefining a top surface and a bottom surface, the bottom surface beingparallel with the top surface; and a first array of microelectrodespatterned onto the top surface of the planar substrate of the flexibleframework, and a second array of microelectrodes patterned onto thebottom surface of the planar substrate of the flexible framework,wherein the first array of microelectrodes is parallel with the secondarray of microelectrodes.
 22. The integrated electrode structure ofclaim 21, wherein the flexible tip portion comprises a plurality oflongitudinally extending arms.
 23. The integrated electrode structure ofclaim 22, wherein: the plurality of longitudinally extending armsinclude a first inboard arm, a second inboard arm, a first outboard arm,and second outboard arm; and the inboard arms and the outboard arms areparallel with one another.
 24. The integrated electrode structure ofclaim 23, wherein a distal end of the first inboard arm is connectedwith the first outboard arm and a distal end of the second inboard armis connected with the second outboard arm.
 25. The integrated electrodestructure of claim 24, wherein: the inboard arms and outboard armsinclude proximal ends; and the proximal ends are disposed within adistal end of the catheter shaft.
 26. The integrated electrode structureof claim 21, further comprising a plurality of conductive tracesdisposed on the flexible framework, each of the plurality of conductivetraces electrically coupled with a respective one of the first andsecond array of microelectrodes.
 27. The integrated electrode structureof claim 26, further comprising a dielectric material disposed betweeneach of the plurality of conductive traces and the flexible framework.28. The integrated electrode structure of claim 27, wherein thedielectric material covers an outer facing surface of each of theplurality of conductive traces.
 29. The integrated electrode structureof claim 21, wherein each of the first and second array ofmicroelectrodes comprises a row of longitudinally-alignedmicroelectrodes aligned parallel to the catheter shaft longitudinalaxis.
 30. The integrated electrode structure of claim 21, wherein eachof the plurality of conductive traces is aligned parallel to thecatheter shaft longitudinal axis.
 31. An integrated electrode structurecomprising: a catheter shaft comprising a proximal end and a distal end,the catheter shaft defining a catheter shaft longitudinal axis; aflexible tip portion located adjacent to the distal end of the cathetershaft and adapted to conform to a tissue, wherein the flexible tipportion includes an inner understructure and an outer understructure,the inner and outer understructure each having a top surface and abottom surface; and a first array of microelectrodes patterned onto thetop surfaces of the inner and outer understructure, and a second arrayof microelectrodes patterned onto the bottom surface of the inner andouter understructure, wherein the first array of microelectrodes isparallel with the second array of microelectrodes.
 32. The integratedelectrode understructure of claim 31, wherein the inner understructureand the outer understructure includes an atraumatic edge that extendsaround a perimeter of the inner understructure and the outerunderstructure.
 33. The integrated understructure of claim 31, furthercomprising a mounting portion connected to the inner understructure andthe outer understructure, wherein the mounting portion includes aplurality of contact pads electrically coupled with the plurality ofmicroelectrodes via the plurality of conductive traces.
 34. Theintegrated understructure of claim 31, wherein the first array ofmicroelectrodes is parallel to the second array of microelectrodes. 35.An integrated electrode structure comprising: a catheter shaftcomprising a proximal end and a distal end, the catheter shaft defininga catheter shaft longitudinal axis; a flexible tip portion locatedadjacent to the distal end of the catheter shaft and adapted to conformto a tissue, the flexible tip portion comprising a first inboard arm,second inboard arm, first outboard arm, and second outboard arm; and afirst array of microelectrodes patterned onto the inboard and outboardarms.
 36. The integrated electrode structure of claim 35, furthercomprising a plurality of conductive traces disposed on the flexibleframework, each of the plurality of conductive traces electricallycoupled with a respective one of the first and second array ofmicroelectrodes.
 37. The integrated understructure of claim 31, furthercomprising a mounting portion connected to the inner understructure andthe outer understructure, wherein the mounting portion includes aplurality of contact pads electrically coupled with the plurality ofmicroelectrodes via the plurality of conductive traces.
 38. Theintegrated electrode structure of claim 35, wherein the first array ofmicroelectrodes is disposed on the inboard and outboard arms via aplating process.
 39. The integrated electrode structure of claim 37,wherein the microelectrodes are ring electrodes.
 40. The integratedelectrode structure of claim 35, wherein a distal end of the firstinboard arm is connected with the first outboard arm and a distal end ofthe second inboard arm is connected with the second outboard arm.